Form 10-IEA sheet for CA firms: which business clients must file it to keep the old tax regime before 21 November 2026 (AY 2026-27)

Updated 22 Oct 2026 · Disclosure: the white-label calendar linked below is an Unadhi product (₹999/year).

What you get: a ready-to-copy Google Sheet layout with one row per business client that tells you, by formula, whether each one needs Form 10-IEA before their return for AY 2026-27: "Nothing to file", "Quote earlier 10-IEA", "File 10-IEA by 21 Nov", "Re-entry is one-time: decide first", or "Past due date". Plus a four-week plan, three made-up example rows and two client messages. Free, no sign-up.

Short answer (checked 22 Oct 2026): the new tax regime is the default. An individual, HUF, AOP (other than a co-operative society), BOI or artificial juridical person with business or profession income who wants the old regime must file Form 10-IEA on or before the due date under section 139(1) of the Income-tax Act, 1961; people without business income just choose in the ITR (Rule 21AGA, Income-tax Rules, 1962; the department's old vs new regime FAQs and Form 10-IEA user manual). For AY 2026-27, CBDT Circular No. 07/2026 (28 Sep 2026) moved the section 139(1) due date for audit cases (Sl. No. 2 of the due-date table: audited non-company assessees and partners of audited firms, where section 92E does not apply) from 31 October to 21 November 2026, a Saturday. The circular does not name Form 10-IEA, so file well before and check which due date the portal offers you in the form (step 8 of the user manual). This is a starting point, not tax advice.

Which due date applies to each client (AY 2026-27)

The due dates are from the department's return of income page (31 Aug / 31 Oct / 30 Nov) and Circular 07/2026. The ITR-3 for AY 2026-27 (Notification No. 47/2026) asks for the due date and the Form 10-IEA acknowledgement number.

Tab "regime": one row per business client

J2: =IF(C2<>"Yes","No 10-IEA: choose the regime in the ITR, filed by the due date",
 IF(F2<>"","New regime only: already re-entered once",
 IF(E2<>"",IF(G2="Old","Stay old: quote earlier 10-IEA in the ITR",
   IF(H2<>"","Re-entry filed: quote "&I2,"Re-entry is one-time: decide, then file 10-IEA by "&TEXT(D2,"d mmm"))),
 IF(G2="New","Nothing to file: new regime is the default",
 IF(H2<>"","Filed: quote "&I2&" in the ITR","File 10-IEA by "&TEXT(D2,"d mmm"))))))
K2: =IF(AND(H2="",TODAY()>D2,OR(LEFT(J2,4)="File",LEFT(J2,8)="Re-entry")),"PAST DUE DATE: check on the portal","")

Sort by column D, then J, so every "File 10-IEA by 21 Nov" row is on top. Column K flags anyone whose due date has gone by without a form.

Three made-up example rows (not real clients)

The rules the formula follows

• Business income: old regime only through Form 10-IEA, filed on or before the section 139(1) due date (Rule 21AGA(1)(a); portal FAQs). Without business income, the choice is made in the return filed under section 139(1) (Rule 21AGA(1)(b)).
• Two forms in a lifetime: one to opt out of the new regime and one to re-enter it (Form 10-IEA user manual, 3.1). Once a business client switches back to the new regime, they cannot choose the old regime again (portal FAQ 11).
• No take-backs in the same year: a Form 10-IEA filed for an assessment year cannot be revoked or withdrawn for that year (portal FAQ 13). Finish the comparison before filing.
• Earlier opt-out carries forward: the AY 2026-27 ITR-3 asks whether a Form 10-IEA for the old regime was filed for an earlier year and, if so, for its acknowledgement number; if the client has not re-entered, the return goes in the old regime (Notification No. 47/2026, ITR-3 Part A General).
• Verification: Form 10-IEA is filed electronically under digital signature or electronic verification code (Rule 21AGA(3)); the user manual walks through e-verification before submission.

Four-week plan to 21 November

Two client messages

1. Regime choice: "Your tax return for FY 2025-26 is due by 21 November 2026. Because you have business income, the new tax regime applies unless we file Form 10-IEA before that date. We are comparing both regimes for you. Please send proof of the deductions you want to claim (for example insurance, investments, home loan interest) by [date], so we can tell you which is lower and file on time."

2. Before going back to the new regime: "You opted for the old regime in an earlier year. The new regime works out lower for FY 2025-26, but for someone with business income, switching back can be done only once, and after that the old regime is not available again. Please reply 'confirm re-entry' if you want us to file Form 10-IEA for this; we will not file it without your written go-ahead."

Notes

• This sheet is for AY 2026-27 (FY 2025-26) under the Income-tax Act, 1961. From tax year 2026-27 the Income-tax Act, 2025 applies; check its rules separately before reusing this sheet next year.
• Business clients whose due date was 31 August 2026 and who did not file Form 10-IEA by then stay in the default new regime for AY 2026-27 unless an earlier opt-out still applies; confirm each case on the portal.
• Re-check the portal before 21 November in case CBDT issues any further order.

Related guides

• ITR chase list for tax-audit clients (21 Nov 2026)
• Tax audit report due date: Circular 7/2026 explained
• Form 3CEB transfer pricing chase list
• November 2026 due-date chase list

Partner programme opening soon

Partner programme opening soon: join the free waitlist. Planned terms are 50% of each referred sale (75% once you have 5+ paying customers), single level, paid through Gumroad only from revenue received.

← All guides

Unadhi Guides are free, independent explainers. We correct errors as soon as we find them: write to mininglife7@gmail.com.