How to File ITR Online: Steps, 17 Mistakes and What I'd Check First

Part of the weekly bookkeeping at our rice mill is matching one record against another, and I don't treat a figure as final until it has been matched against its source, whether it is going to the CA or to the bank. An income tax return deserves the same habit. The portal hands you a draft built from other people's reporting, and your job is to check it against your own records before you submit it.

Filing an income tax return used to mean queues, paper forms, and a visit to a tax practitioner. Today, for most salaried Indians, it is a free online process that can be finished in under an hour: the tax department pre-fills most of your data, and you mainly verify and correct it. Most people assume that means copying numbers from Form 16 into the portal, and that is where a lot of filing mistakes start. A complete, accurate return usually needs more than one document, and the small gaps between them (a bank that reports interest differently than you expected, a broker statement that doesn't match your own trade log, an old employer's TDS that never showed up) are exactly what lead to tax-credit mismatches, delayed processing, or a request for clarification.

This guide takes you through the entire sequence on the official portal at incometax.gov.in for FY 2025-26 (AY 2026-27): what to gather, which form to pick, how to use the pre-filled data sensibly, and the critical final step of e-verification that many first-timers forget. It then walks through the 17 mistakes that most commonly cause mismatches, refund delays and notices, with a clear way to avoid and fix each one, and what changes if you file after the due date.

Before You Start: Gather Your Documents

Filing is fast when your inputs are ready. Pull these together first:

• PAN and Aadhaar, which must be linked, because an unlinked PAN can become inoperative and block filing.
• Form 16 from your employer, summarising salary and TDS. Understand it using our Form 16 explained guide.
• Form 26AS and the AIS (Annual Information Statement), downloaded from the portal. These show the tax credited and the high-value transactions reported against you. See Form 26AS and AIS.
• Bank details, including a pre-validated account for any refund, and interest certificates for savings/FD interest.
• Proof of deductions you intend to claim: 80C investments, 80D health insurance, home loan interest, and so on (relevant under the old regime).
• Capital gains statements from brokers or mutual funds, if any.

AIS, TIS, and Form 26AS often get treated as the same thing. They're not. Form 26AS is essentially a tax-credit statement: it shows TDS, TCS, advance tax, and self-assessment tax linked to your PAN. AIS is much broader: it pulls in bank interest, dividends, securities transactions, mutual fund activity, foreign remittances, and property transactions reported by various institutions. TIS (Taxpayer Information Summary) is a simplified, de-duplicated version of AIS meant for quick reference and pre-filling your return. None of the three is guaranteed to be complete or error-free. They reflect what reporting entities have submitted, and duplication or misclassification does happen. Use them as a cross-check, not as a substitute for your own records.

Here is what to check in each document, and where mismatches usually come from:

Our tax document checklist is a handy way to make sure nothing is missing before you log in.

Step 1: Log In and Confirm Your Profile

Go to incometax.gov.in and log in with your PAN (which serves as your User ID) and password. First-time users register using their PAN. Once in, confirm that your contact details, bank accounts, and Aadhaar link are correct under your profile. A pre-validated bank account is essential: refunds are only credited to a validated account.

Step 2: Choose the Right Form and Regime

The portal will guide you, but it helps to know which ITR form fits your situation:

Note on section numbers: the Income-tax Act, 2025 (effective 1 April 2026) consolidated Sections 44AD, 44ADA, and 44AE into a single Section 58, confirmed against the Income Tax Department's official transition FAQ and the Act's own text. The rates and thresholds behind the presumptive-eligibility row above are unchanged.

Our which ITR form guide explains the choice in detail.

You will also select your tax regime. The new regime is the default; choose the old regime only if your deductions justify it. Work this out beforehand using our old vs new tax regime guide, because for most salaried filers the regime decision drives the entire return.

Step 3: Review the Pre-Filled Data Carefully

This is the step that matters most. The portal pre-fills your return with data it already holds: salary from your employer's TDS return, interest reported by banks, TDS from Form 26AS, and high-value transactions from the AIS.

Do not blindly accept it. Reconcile every pre-filled figure against your own documents:

• Does the salary match your Form 16?
• Does the TDS match Form 26AS?
• Is the interest income complete? The AIS sometimes misses small amounts, and sometimes double-counts. Both happen.
• Are your capital gains correctly reflected?

If the pre-filled data is wrong, correct it. You are responsible for the final figures, not the portal. Mismatches between what you file and what the AIS shows are the leading cause of income tax notices, so reconciliation is not optional.

Step 4: Enter Deductions and Compute Tax

If you are on the old regime, enter your deductions in the relevant schedules: 80C up to ₹1.5 lakh, 80D for health insurance, home loan interest under Section 24(b), HRA (compute it with our HRA exemption calculator), and NPS under 80CCD(1B). Under the new regime, most of these are not allowed, so the deduction schedules stay largely empty.

The portal then computes your tax automatically, showing whether you owe additional tax or are due a refund. If tax is payable, pay it online via the e-pay tax facility (Challan 280, self-assessment tax) and enter the challan details before submitting. A large balance at this stage usually means income that TDS never covered, which is worth planning for next year through advance tax.

A Worked Example: One Salaried Return, Reconciled

Take a salaried professional in Mumbai filing for FY 2025-26. Her Form 16 shows:

• Gross salary: ₹14,00,000
• TDS deducted by employer: ₹95,000
• She is on the new regime (her employer deducted TDS accordingly).

On the portal:

1. She logs in; salary of ₹14,00,000 and TDS of ₹95,000 are pre-filled.
2. She checks Form 26AS: the ₹95,000 TDS matches. Good.
3. She checks the AIS and notices ₹12,000 of savings-bank and FD interest that was not in the pre-filled salary data. She adds it as income from other sources.
4. Her taxable income becomes ₹14,00,000 − ₹75,000 standard deduction + ₹12,000 interest = ₹13,37,000.
5. The portal computes tax under the new regime slabs. On ₹13,37,000 taxable it works out to about ₹83,772 including cess.
6. Since ₹95,000 was already deducted as TDS, more than her ₹83,772 liability, she is due a refund of about ₹11,200. She double-checks her pre-validated bank account so the refund can be credited.
7. She submits and then e-verifies via Aadhaar OTP.

Had she ignored the ₹12,000 interest the AIS already knew about, she would likely have received a mismatch notice later. Reconciliation took her five minutes and saved that hassle.

The Three Matches I'd Make Before Pressing Submit

At the mill, the discipline that keeps the books honest takes no special skill. It needs someone who insists that two records of the same thing agree before either one is trusted.

A tax return needs three such matches:

1. Tax credits against Form 26AS. Every rupee of TDS, advance tax and self-assessment tax you claim should appear in Form 26AS against your PAN. If it doesn't, the fix lies with the deductor or the challan, not in your return.
2. Income against your own records. Each AIS line (interest, dividends, sales of shares or units, rent) should match a bank or broker record you can point to. Duplicates come out; missing items go in, even when no TDS was deducted.
3. The portal's tax against your own estimate. Before paying any balance or accepting a refund figure, compare the computed tax with a rough figure of your own. The income tax calculator on this site gives a quick salary-based estimate under either regime. A large gap usually means an entry went into the wrong schedule.

If a CA files for you, these checks are still yours. The pre-filled data is other people's reporting, and the CA works from what you hand over. The accuracy of that stays with the person whose name is on the return.

Step 5: Submit and E-Verify (The Step People Forget)

After submission, your return is not complete until you e-verify it. You have 30 days to do so. If you do not, the return is treated as invalid, as if you never filed.

The fastest method is an Aadhaar OTP sent to your Aadhaar-registered mobile, which verifies instantly. Other options:

• Net banking login to the tax portal
• EVC through a pre-validated bank or demat account
• A Digital Signature Certificate (DSC)
• Posting a signed physical ITR-V to the CPC in Bengaluru within the same 30 days (slowest; only if you cannot e-verify)

Once verified, you will receive a confirmation, and the return goes for processing. Any refund follows to your pre-validated bank account.

Online vs Offline Utility: Which to Use

The portal offers two ways to file, and beginners often pick the harder one by accident.

• Online (in-browser) filing: you fill the form directly on the portal, with pre-filled data loaded automatically. This is the simplest route and is ideal for ITR-1 and ITR-4, and increasingly for ITR-2. Everything happens in your browser; nothing to download.
• Offline utility (JSON): you download the department's utility, fill it on your computer, generate a JSON file, and upload it. This suits complex returns (ITR-2 and ITR-3 with many schedules) and lets you work without a constant internet connection. It also helps if your return is large enough that the browser feels sluggish.

ITR-1, ITR-2, ITR-3 and ITR-4 are currently live on the e-filing portal for AY 2026-27, with Excel utility, online, and offline filing all available. For most salaried filers, the online route is faster and less error-prone. Reach for the offline utility only if your return is complex or the in-browser form is struggling with the volume of entries.

ITR Filing Mistakes to Avoid

In short: the most common ITR filing mistakes in 2026 include choosing the wrong ITR form, missing income such as FD interest or freelance receipts, ignoring AIS or Form 26AS mismatches, selecting a tax regime without comparing both, misreporting capital gains or F&O income, claiming unsupported deductions, and forgetting to e-verify the return after submission.

Mistake 1: Selecting the wrong assessment year

The FY/AY naming trips people up: the year you earned the income (FY 2025-26) isn't the year you file it (AY 2026-27). Picking the wrong year can mean the return gets filed against the wrong period entirely.

Remember it this way: FY is when you earned the money, AY is when you assess and file it. For income earned between 1 April 2025 and 31 March 2026, the AY is 2026-27. If you catch this before the due date, just start a fresh return under the correct year; after filing, you'd typically need a revised return instead. Check before filing: confirm "AY 2026-27" shows at the top of your return before entering a single figure.

Mistake 2: Choosing the wrong ITR form

Taxpayers often reuse the form they filed last year without checking whether their income sources changed. A return filed on the wrong form can be treated as defective: you'll typically get a notice under Section 139(9) giving you 15 days, or the period specified in the notice, to refile using the correct form.

Match your actual income sources (salary, house property, capital gains, business or professional income, presumptive taxation) against form eligibility, rather than picking whatever feels simplest; the form table in Step 2 sets out the conditions. If you haven't e-verified yet, you can generally withdraw and refile on the correct form before the due date; after verification, a revised return is usually the route.

Example: an investor who sold shares held for two years, alongside a salary, needs ITR-2, not ITR-1, since capital gains beyond the small permitted LTCG limit fall outside ITR-1's scope.

Mistake 3: Filing only from Form 16

Form 16 feels authoritative because the employer prepares it, so it's tempting to treat it as the whole story. It isn't. Savings and FD interest, dividends, freelance receipts, rental income, and income from another employer all live outside it.

Treat Form 16 as one input among several: cross-check interest and dividend income against AIS, and add anything freelance or rental separately. If it's already filed and something's missing, a revised return can add it. Example: a salaried employee with ₹40,000 in FD interest and ₹15,000 in dividend income needs to add both; Form 16 only reflects the salary.

Mistake 4: Ignoring mismatches between AIS, TIS, Form 26AS and your own records

AIS can carry duplicated entries (the same transaction reported by two intermediaries) or figures that simply don't match what happened. Copying an inflated AIS figure overstates income; ignoring a genuine one understates it. Either way raises the odds of a mismatch query.

Reconcile AIS against your bank and broker records line by line, and use the official AIS feedback option where something's wrong, rather than silently ignoring it or blindly copying it in. Example: a taxpayer's AIS shows the same ₹25,000 bank interest twice because two branches reported it separately; reporting it twice in the ITR would overstate income. For repeated or complex mismatches, professional help is worth the cost.

Mistake 5: Reporting tax credits that don't appear correctly

A deductor filing late, using the wrong PAN, or making a challan error can all mean TDS, TCS, advance tax, or self-assessment tax doesn't show up the way you expect in Form 26AS. None of it is your fault, but it still affects processing.

Match every TDS/TCS entry and every challan against Form 26AS before claiming it. If a genuine credit is missing, follow up with the deductor to get their filing corrected rather than simply dropping a legitimate claim. Example: an employer deducts ₹18,000 TDS that hasn't yet reflected in Form 26AS due to a filing delay on their end. The fix is to follow up with payroll, not to assume the credit is gone.

Mistake 6: Selecting the wrong tax regime

The new regime is now the default, so a lot of taxpayers stay in it automatically without checking whether the old regime, with its deductions, actually works out cheaper for their specific numbers.

For FY 2025-26, the new regime has a ₹4 lakh basic exemption, a ₹75,000 standard deduction, and a Section 87A rebate that makes taxable income up to ₹12 lakh effectively tax-free, which for a salaried taxpayer means gross salary up to about ₹12.75 lakh, once the ₹75,000 standard deduction is applied. The old regime keeps its earlier slabs, a ₹50,000 standard deduction, and a rebate only up to ₹5 lakh income, but it still allows deductions like 80C, 80D, and home loan interest that the new regime largely doesn't. Compute both before deciding; don't assume either one wins by default. The old vs new tax regime guide walks through the comparison with worked numbers.

Salaried taxpayers without business income can switch regimes every year directly in the ITR, provided they file it by the due date; a belated return is taxed under the new regime. Taxpayers with business or professional income need to file Form 10-IEA by the due date to opt for the old regime, and once they exit the old regime, re-entry is restricted for as long as they continue to have business income. Example (illustration only): a salaried person with ₹12 lakh taxable income and modest 80C/80D claims may find the new regime cheaper purely on the rebate, while someone with a large home loan interest claim and full 80C utilisation might still do better under the old regime. The right answer depends on your own numbers, not a rule of thumb.

Mistake 7: Forgetting income from a previous employer

After a mid-year job change, each employer only knows about the salary they paid, so slab calculations and standard deduction may not account for the full year, and combined TDS often falls short once both incomes are added up.

Collect Form 16 from every employer for the year and consolidate the total salary, including joining bonus, leave encashment, or arrears, before filing. Example: someone who worked at two companies during FY 2025-26, each deducting TDS as if they were the sole employer, may find combined income pushes them into a higher slab, requiring a small top-up payment at filing time.

Mistake 8: Missing savings account, FD, RD and other interest income

There's a common assumption that if no TDS was deducted, the income isn't taxable. It isn't correct: interest is taxable regardless of TDS, and submitting Form 15G or Form 15H (Form 121 from tax year 2026-27) only stops the bank from deducting TDS; it doesn't exempt taxable interest.

Report all interest income for the year, TDS or not, under "Income from Other Sources." Tax on FD and savings interest sets out the rules and the TDS thresholds. Example: a retired person with ₹3 lakh in FD interest and no TDS deducted, because Form 15H was submitted, still needs to report that interest if their total income is taxable.

Mistake 9: Missing dividend or miscellaneous income

Dividends, freelance receipts, commission, and family pension often feel too small or irregular to "count," especially spread across several platforms, but they add up, and AIS usually picks up more of them than people expect.

Go through the year's bank statement specifically looking for dividend credits, freelance payments, or commission income, and report them under the correct schedule. Example: a software professional who did occasional freelance work worth ₹80,000 over the year needs to report that separately from their salary.

Mistake 10: Reporting stock and mutual fund transactions incorrectly

Broker capital-gains statements are convenient, but they're a computational aid, not automatically the final legal position: bonus shares, splits, and buybacks can affect cost of acquisition in ways the statement doesn't always capture correctly.

Compute the taxable gain (sale value minus cost of acquisition, split by holding period) rather than relying on sale value or the broker PDF alone. For transfers on or after 23 July 2024, short-term gains on STT-paid listed equity and equity mutual funds are taxed at 20%, and long-term gains on the same at 12.5% with a ₹1.25 lakh annual exemption. Rates can differ for debt-oriented funds and for transactions before that date, so don't assume one rate covers every holding. The capital gains tax guide covers the mechanics in full, including LTCG and STCG on stocks. Example (illustration only): a broker statement shows ₹2 lakh as "capital gain" for a stock that included a bonus issue; recomputing the cost of acquisition after the bonus might show a different taxable gain.

Mistake 11: Treating futures and options or intraday trading as normal capital gains

Both involve buying and selling securities, so it's easy to assume the same tax treatment applies as investing. It doesn't. F&O trading is generally non-speculative business income, reported under ITR-3. Intraday equity trading (buying and selling the same share the same day without delivery) is speculative business income, with its own separate loss rules. Delivery-based investing is usually capital gains, though high-frequency delivery trading can sometimes need separate analysis.

Misclassifying either as capital gains affects the applicable ITR form, allowable expenses, and loss carry-forward eligibility. Example (illustration only): a trader with F&O turnover (the absolute sum of profits, losses, and options premium) crossing ₹1 crore may need a tax audit under Section 44AB, unless at least 95% of transactions are non-cash, which raises the threshold to ₹10 crore. Whether audit actually applies depends on the full picture, not turnover alone. High-volume derivatives trading, or anything near the audit threshold, is worth a conversation with a qualified tax professional before filing.

If you trade F&O and would rather not rebuild that turnover figure at filing time, I made the F&O & Intraday Trading Journal, my own Google Sheets template that records the charges on every trade and works out tax-audit turnover by the ICAI method, with intraday and F&O kept apart. It's ₹1,499 on Gumroad. It keeps records; it gives no trading advice.

Mistake 12: Ignoring crypto and virtual-digital-asset transactions

Crypto tax rules are newer and less familiar than most, and transactions are often spread across multiple exchanges and wallets, easy to lose track of when there's no single consolidated statement.

Since VDA-related TDS is reported to AIS and Form 26AS under Section 194S, an unreported transfer can create a visible gap between what's disclosed and what tax was already deducted. Report every transfer in Schedule VDA, including transfers across exchanges and gifted VDAs. Gains are taxed flat at 30% with no deduction beyond cost of acquisition, and losses from one VDA can't be set off against gains from another VDA or any other income. The crypto tax in India guide has the full breakdown. Example: someone who moved coins between two exchanges and sold on the second one needs to report the transfer using records from both platforms, not just the one where the final sale happened.

Mistake 13: Incorrect house-property and home-loan reporting

Rules around self-occupied versus let-out property, and co-borrower versus co-owner status, aren't always intuitive. Being a co-borrower on a loan doesn't automatically entitle you to a deduction if you're not also a co-owner of the property.

Report rental income and claim home loan interest strictly in proportion to actual ownership share. Pre-construction interest is claimed in five equal instalments starting from the year construction is completed, separate from regular annual interest. The home loan tax benefits guide covers the ownership and documentation rules in detail. Example: a property jointly owned 70:30 by spouses should have rental income and home loan interest split 70:30, not claimed entirely by whoever manages the bank account.

Mistake 14: Claiming unsupported or ineligible deductions

Pre-filled portal data can create a false sense that a deduction is automatically validated, when it's really just carried over from a previous filing or a third-party report. Most Chapter VI-A deductions (80C, 80D, donations, education-loan interest, NPS under 80CCD(1B)) also aren't available at all under the new regime.

Check that the investment or payment date falls within FY 2025-26, that the payment mode qualifies, and that any relationship or ownership condition is actually met, and keep receipts on hand even after filing. The income tax deductions guide lists what documentation each one actually requires. Example: a taxpayer under the new regime who still enters an 80C deduction meant for the old regime needs to remove it before filing.

Mistake 15: Incorrectly setting off or carrying forward losses

Different loss categories (capital, business, house property, speculative, F&O, VDA) each follow their own set-off and carry-forward rules, and it's easy to apply one rule universally across all of them.

Filing on or before the due date is generally required if you want to carry forward capital losses or non-speculative business losses (what a late return forfeits). Speculative losses, like intraday trading, can typically only be set off against speculative income, and VDA losses can't be set off or carried forward against anything at all. Example (illustration only): a trader with a ₹1.5 lakh intraday trading loss can't adjust it against salary; it can only be set off against speculative gains, in the same year or carried forward against future speculative gains.

Mistake 16: Entering incorrect personal or bank details

PAN, Aadhaar, name, date of birth, address, email, mobile number, and bank account/IFSC fields are often auto-filled or copied from an old return without being rechecked, and a closed or dormant refund account is one of the more preventable causes of a stuck refund.

Confirm PAN-Aadhaar linkage, make sure your registered email and mobile are ones you actually check, and pre-validate the bank account you want the refund credited to. Example: a taxpayer who closed their salary account after switching jobs but never updated it in the e-filing profile finds the refund can't be credited until the account is corrected.

Mistake 17: Filing the return but failing to e-verify it

Filing feels like the finish line, so the separate verification step gets skipped or forgotten, but an unverified return is treated as not filed at all, and that affects everything downstream, including refund processing.

E-verify within 30 days of filing, ideally immediately, using one of the methods in Step 5. Example: someone who filed on 20 July but only e-verifies on 25 August has missed the 30-day window and needs to request condonation of delay rather than assume the filing still stands.

Refunds: How and When

If your TDS and advance tax exceed your final liability, you are due a refund, credited directly to your pre-validated bank account linked to your PAN. Once your return is processed by the Centralised Processing Centre, the refund is usually issued within a few weeks for straightforward returns, though timing varies with volume.

Why Your Refund Can Be Delayed Even After Filing

A delay doesn't automatically mean something's wrong; most returns simply take time to move through processing. The common reasons: the return isn't e-verified yet; it's still under processing, especially during the peak July-August window; there's an AIS or tax-credit mismatch under review; the bank account isn't validated, is incorrect, or doesn't match your PAN; an outstanding demand from an earlier year gets adjusted against the current refund; or a deductor hasn't corrected their TDS filing yet, so the credit doesn't reflect on the department's end.

A normal processing delay usually resolves on its own. An error requiring correction (a mismatch, an invalid bank account, or a defective-return notice) needs you to act before the refund can move. Checking your return's status and AIS on the portal is the fastest way to tell which one you're dealing with.

Interest is payable by the department on delayed refunds in certain cases, but the cleanest path to a fast refund is an accurate, reconciled return filed early with a validated account.

Mind the Deadline

For AY 2026-27, the due date depends on the kind of income you have. This is a genuine change from earlier years, so don't assume last year's date. The statute sets the later date for an assessee with income from business or profession whose accounts are not required to be audited (and for a non-audit partner of a firm), which in practice means the ITR-3 and ITR-4 filers:

The ITR-3/ITR-4 non-audit extension is a real, current-year change: it gives freelancers, consultants, and presumptive-scheme filers a full month longer than salaried ITR-1/ITR-2 filers. It is not an informal relaxation; treat your own applicable date as firm. For a small business or freelancer, the extra month is useful working time: it gives you room to let outstanding receivables settle, reconcile GST turnover against your bank statement, and finalise business income before locking in the return, rather than closing the books in a rush to meet a salaried employee's deadline.

Filing by your applicable date is what preserves loss carry-forward and keeps late fees and interest off the bill. Miss it and you can usually still file a belated return until 31 December of the assessment year, but it costs a late fee, interest on any unpaid tax and the right to carry most losses forward. Leaving it to the last day carries a risk of its own: the portal slows down near deadlines and errors are easy to make under time pressure.

One limitation worth flagging: government due dates are sometimes extended by CBDT circular in response to portal load or representations from tax bodies; this has happened in past years. Check the "Latest Updates" section on incometax.gov.in for any extension before relying on the dates above.

Filing After the Due Date: Belated Returns and What You Lose

Missing the due date happens; the year gets busy. You can still file, but the later you file, the more you lose. Before assuming you are late, check which of the due dates above is actually yours: if you freelance or have other business or professional income without an audit, yours was 31 August, not 31 July.

The Windows After the Due Date

A belated return is a first filing, done late. A revised return corrects errors or omissions in a return you have already filed, and replaces it. You can revise a belated return, and the outer deadline is the same one an on-time filer has: twelve months from the end of the year (31 March 2027 for AY 2026-27) or the completion of your assessment, whichever comes first. That window used to close at nine months, on 31 December. The Finance Act 2026 substituted a new Section 263(5) in the Income-tax Act, 2025 running to twelve months, and made the matching change to the old Act's Section 139(5).

So the revision window now closes three months after the belated one does, and the two deadlines are no longer the same date, and that is the single most common thing people get wrong about this. The second most common is assuming those three months are free. They are not. The Finance Act 2026 inserted Section 234-I into the Income-tax Act, 1961, charging a fee on a revised return furnished late in the window: ₹1,000 if your total income does not exceed ₹5 lakh, and ₹5,000 in any other case. Revise on or before 31 December 2026 and it costs nothing. 31 December is still the date to aim at; 31 March is the date you buy.

Treat 31 December 2026 as the date to act on rather than a settled statutory boundary. Section 234-I as printed charges the fee on a revised return furnished beyond nine months but before twelve months from the end of the relevant assessment year, which, read literally, would fall entirely after Section 139(5) has already closed the window, so the fee could never apply. The Finance Bill's Notes on Clauses instead describe it as nine months from the end of the relevant previous year, and that is the reading which produces 31 December 2026 and lets the charge operate at all. Until the department clarifies, revising by 31 December 2026 is free on either reading. The Income-tax Act, 2025 carries the same fee in the same amounts as Section 428(b), where it is measured unambiguously from the end of the tax year (in practice, any revision filed on or after 1 January) for the years it governs. Both changes to that Act, the longer window and the fee, took effect on 1 April 2026, so they apply from tax year 2026-27.