Compliance due dates in September 2026

September is the heaviest month in the calendar

Three unrelated things converge. The AGM must be held within six months of the financial year end, so 30 September for a 31 March year end — and the AOC-4 and MGT-7 deadlines that follow are measured from the AGM date, meaning a late AGM makes two later filings late automatically. DIR-3 KYC is due for every person holding a DIN on the same day. And the tax audit report falls due for companies in the audit bracket.

The dependency is what makes September unforgiving: the AGM needs audited accounts, the audit needs closed books, and none of that can be compressed into the last fortnight. Work backwards from 30 September and the real deadline for a clean book close is months earlier.

DIR-3 KYC is worth flagging separately because it is a per-director obligation rather than a company one, so nobody in the company's own process necessarily owns it. Miss it and the DIN is deactivated, which blocks that person from signing every other filing on this list.

What actually happens when you miss one — beyond the late fee

Founders under-rate compliance because they assume the worst case is a fee they can pay later. For the routine monthly filings that is broadly true. For several of these it is not, and the real consequences are structural rather than financial.

The amounts and rates are deliberately not stated here, because they change and because a number without its working is worth little. Where we can compute one, the calendar rows link a calculator that shows the arithmetic.

Losing your carried-forward losses — the expensive one for startups

Business losses may only be carried forward to set off against future profits if the return for the loss year was filed by the due date under Section 139(1). File late and, under Section 139(3) read with Section 80, that year's business loss is simply gone. A startup burning cash for four years is accumulating its single most valuable tax asset; a missed filing deadline destroys that year's slice of it, and there is no way to restore it later. Unabsorbed depreciation is treated differently, which is cold comfort.

Director disqualification

Under Section 164(2), a director of a company that has not filed its financial statements or annual returns for three consecutive financial years is disqualified — and the disqualification attaches to the person, barring them from being a director of ANY company, not merely the defaulting one. Founders discover this when they try to incorporate their next venture.

The company being struck off

The Registrar may strike a company off under Section 248 where it is not carrying on business or has not filed for a sustained period. Restoration means an application to the Tribunal — slow, costly, and fatal to any fundraise or acquisition in progress.

DIN deactivation

Miss DIR-3 KYC and the director's DIN is deactivated until it is filed with the prescribed fee. A deactivated DIN blocks that person from signing filings, which stalls everything else on this page.

Blocked GST filings and cancelled registration

Non-filing compounds: an unfiled GSTR-3B blocks the subsequent GSTR-1 under Rule 59(6), so one missed month freezes the next, and sustained non-filing is a ground for cancellation of registration under Section 29. Interest on the tax itself runs under Section 50 independently of any late fee.

Disallowed expenditure on unpaid TDS

Beyond interest under Section 201(1A) and the fee under Section 234E for late returns, failing to deduct or deposit TDS can cause the underlying expense to be disallowed under Section 40(a)(ia) — you lose the deduction on the payment itself, which usually costs more than the interest.

Advance tax interest

Under Sections 234B and 234C, interest runs on shortfalls in advance tax instalments. This one bites profitable companies that only think about tax at year end, and it accrues quietly across the four instalment dates.