Is GST charged on income?

No. GST is a tax on taxable supplies; income is an accounting or direct-tax concept.

When does the 180-day period start?

It is counted from the invoice date under the statutory condition.

What happens on partial payment?

The reversal is generally proportionate to the unpaid amount.

Does reverse charge follow this rule?

The 180-day payment condition does not apply to supplies on which tax is payable under reverse charge.

Can reversed ITC be reclaimed?

It can generally be re-availed after payment to the supplier, subject to Rule 37.

Should interest be calculated automatically?

Yes, but the tool must use the rate and start/end dates legally effective for the period.

GST

GST 180-day ITC reversal under Rule 37: calculation and reclaim file

Reviewed by CA Nikhil Gupta - source checked for this batch on 1 October 2026

The 180-day rule is a payment-condition control. If the recipient does not pay the supplier the value of supply plus tax within 180 days from the invoice date, ITC may need to be reversed and later reclaimed when payment is made.

Primary source trail

The main sources are section 16(2), Rule 37 and CBIC's GSTR-3B reporting circular. Keep the invoice-wise working with the GSTR-3B table used for reversal/reclaim.

Trigger

Non-payment of supplier consideration plus tax within the prescribed 180-day period from invoice date.

Not permanent

The reversal is normally temporary. Credit can be reclaimed when the recipient makes the payment, subject to current law and reporting.

Reporting

Circular 170/02/2022-GST places reclaimable reversals such as Rule 37 in GSTR-3B Table 4(B)(2), with reclaim in Table 4(A)(5) and disclosure in Table 4(D)(1).

Exceptions

Reverse-charge supplies, deemed-payment transactions and credit-note or dispute settlements need separate review before reversing mechanically.

Bare law and source decode

Section 16(2) links entitlement to ITC with possession of tax document, receipt of supply, tax payment to Government and return furnishing by supplier conditions.
The 180-day payment proviso focuses on payment by the recipient to the supplier for the value of supply plus tax.
Rule 37 prescribes the manner of reversal and subsequent re-availment when payment is later made.
The working should be invoice-wise. A vendor-level lump sum can hide part payments, credit notes, retentions and disputed supplies.
Interest exposure depends on the period and manner of reversal under the current rule text and portal reporting.

Workflow

Export invoice-wise ITC availed from books, GSTR-2B and purchase register.

For each invoice, compute the 180th day from invoice date and compare actual payment date and amount.

Remove cases where reverse charge, deemed payment or valid credit-note adjustment changes the test.

Compute proportionate ITC reversal for unpaid value plus tax and tie it to GSTR-3B Table 4(B)(2).

When payment is made, reclaim eligible ITC with invoice, bank and vendor-ledger evidence.

Practical examples

Invoice value Rs.100 plus GST Rs.18. If Rs.59 is paid and Rs.59 remains unpaid after 180 days, test proportionate reversal rather than reversing all ITC automatically.
A retention amount held under contract should be reviewed against the rule text and actual payment obligation. Do not treat every retention as safe without source support.
A debit note or commercial dispute should be reconciled with vendor ledger and tax document before deciding the reversal amount.

Highlighted points

Do not compute from due date; start from invoice date unless the official rule or transaction-specific position requires otherwise.
Do not ignore part payments.
Do not reclaim without bank/vendor ledger proof.
Keep Rule 37 reversals separate from Rule 42/43 exempt-supply reversals.

Exam and advisory case study

Advisory case: A company reverses all ITC for a vendor even though only 20 percent of invoices crossed the 180-day threshold. The correct file is invoice-wise: invoice date, ITC availed, payment made, unpaid balance, reversal month and reclaim month.

Finin2min Summary

Rule 37 is a working-file rule. The safe file has invoice-wise ageing, payment evidence, exception tagging, GSTR-3B reporting and reclaim support.

Q&A

Can ITC be reclaimed later?

Yes, where the legal conditions are satisfied and payment is made. Keep the payment trail and reclaim disclosure.

Is Rule 37 the same as blocked credit?

No. Blocked credit under section 17(5) is different from a payment-condition reversal.

Which table is relevant in GSTR-3B?

CBIC Circular 170/02/2022-GST discusses temporary reversals in Table 4(B)(2), reclaim in Table 4(A)(5) and disclosure in Table 4(D)(1).