Short answer: if a micro or small enterprise is unpaid beyond the permitted window at 31 March, the deduction is disallowed that year and allowed only when you pay. The usual escape — pay before the return due date — does not apply here. It is the only entry in the section that works this way.
Why this one is different
Deductions allowed on actual payment sit at s.37 of the Income-tax Act, 2025 (the old 43B). The familiar mechanics are forgiving: an amount incurred but unpaid at year end is still deductible if it is paid before the due date for filing the return. Most businesses run their year-end on exactly that basis.
The MSME clause removes that relief. For payments to micro and small enterprises beyond the time limit under the MSMED Act, the proviso simply does not apply.
The consequence is stark. On 31 March the position is fixed. There is no remedial payment, no filing-date rescue, no reasonable-cause argument. The deduction moves to the year of payment.
That is why this rule belongs in the March conversation and not the September one. By the time the return is being prepared, the only remaining question is how large the disallowance is.
The window: 45 days, or 15
| Situation | Limit |
|---|---|
| Written agreement specifying credit terms | As agreed, capped at 45 days |
| No written agreement | 15 days |
An agreement cannot extend the period beyond 45 days — a 90-day credit term written into a purchase order does not give 90 days for this purpose.
The commonly missed half is the second row. Businesses assume 45 days as a default. Without a written agreement the limit is 15 days, which most manufacturing payment cycles do not meet. If you are relying on 45 days, the agreement that gives it to you should exist and should be locatable.
Who it actually catches
Three filters, and each is a place where businesses over-apply the rule as often as they under-apply it.
Micro and small only. Medium enterprises are outside it. The three categories are defined by investment and turnover thresholds, and a supplier's Udyam certificate states which one they fall into. Holding the certificate is not the same as having read it.
Traders are generally outside it. Traders can hold Udyam registration, but that registration exists for other purposes and this disallowance is generally treated as not reaching them. Businesses that disallow every Udyam-registered creditor indiscriminately create a provision larger than the law requires.
Registration matters. The protection under the MSMED Act runs to enterprises holding registration. An unregistered small supplier does not bring the clause into play.
The practical problem: you do not have the data
The rule is arithmetically simple and operationally hard, because it needs something most creditor ledgers do not carry:
- Is this supplier registered under Udyam?
- Are they micro, small or medium?
- Are they a manufacturer or service provider, or a trader?
- What does the written agreement say, and does one exist?
- What is the age of each outstanding invoice against the right window?
None of that appears in a standard purchase ledger. It has to be collected from suppliers, and collected before year end to be useful.
The businesses that handle this well capture Udyam status and category at supplier onboarding and age MSME creditors separately through the year. The ones that handle it badly send a circular to suppliers in the third week of March.
What it costs beyond the deduction
Two further consequences, both frequently overlooked:
- Interest under the MSMED Act on delayed payment — at a penal multiple of the bank rate, payable to the supplier, and not deductible. It accrues whether or not the supplier claims it.
- Disclosure in the financial statements of amounts outstanding to MSME suppliers, which makes the position visible to auditors, lenders and anyone reading the accounts.
Before this 31 March
- Get Udyam status and category for every material creditor — micro, small, medium, and manufacturer, service provider or trader.
- Identify which have written agreements, and what those say about credit terms.
- Age the MSME creditors separately against 45 or 15 days as applicable.
- Quantify the disallowance as if the year closed today.
- Decide which to pay before 31 March — this is the only point at which the decision exists.
For companies, the same exercise feeds the audit disclosure, so doing it once serves both. See also what a tax audit season actually requires.
This is a working reference, not the statute. For anything you are relying on, confirm the section text and the MSMED Act limits directly.