ITC Reversal Under Rule 37: The 180-Day Rule, Rule 37A & Practical Difficulties

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GST · ITC Series · Part 6 of 7

ITC Reversal Under Rule 37:
The 180-Day Rule & Practical Difficulties

What triggers the reversal, how interest bites, when you can re-claim — and the real-world scenarios where Rule 37 creates compliance headaches.

📅 25 April 2026 ✍️ TaxRoutine Research Team 📖 ~12 min read 🏷️ GST · Rule 37 · ITC Reversal · 180-Day Rule
📚 ITC Under GST — Complete Series (7 Parts)

📌 At a Glance

  • Rule 37 implements the proviso to Section 16(2)(b) — if the supplier is not paid within 180 days of the invoice date, ITC must be reversed.
  • Reversal is required in the GSTR-3B of the month in which the 180th day falls, filed through the GST portal.
  • Interest at 18% p.a. under Section 50(1) applies from the date ITC was claimed to the date of reversal.
  • On subsequent payment to the supplier, the ITC can be re-claimed in the period of payment.
  • Rule 37A introduces a parallel track — reversal when the supplier has not filed GSTR-3B, regardless of buyer’s own payment.
  • Practical difficulties include tracking deadlines across hundreds of invoices, disputed payments, credit notes, partial payments, and barter/non-monetary consideration.

1. Statutory Basis: Section 16(2)(b) & Rule 37

The 180-day rule has its roots in the proviso to Section 16(2)(b) of the CGST Act. The proviso states that where a registered person fails to pay the supplier the amount towards the value of supply along with the tax payable thereon within 180 days from the date of issue of the invoice, an amount equal to the ITC availed shall be added to the output tax liability — along with interest under Section 50.

Rule 37 of the CGST Rules, 2017 operationalises this proviso. It prescribes when the reversal must be made, how to calculate the proportionate reversal for partially-paid invoices, and how the re-credit works once payment is eventually made.

📖 The Policy Rationale

The 180-day rule exists to prevent ITC from becoming a tool for leveraging unpaid credit. Without this rule, a buyer could claim full ITC on an invoice and then indefinitely delay paying the supplier — effectively getting a free float on the tax credit at the government’s expense. The rule ensures that ITC is tied to the underlying commercial transaction being genuinely completed. Read the full text of Section 16 on CBIC.gov.in →

2. How Rule 37 Works: Step by Step

Invoice Date — Day 0
Supplier issues a tax invoice. Buyer receives goods or services. ITC is claimed in the GSTR-3B for that period — assuming the invoice reflects in GSTR-2B on the GST portal and all Section 16(2) conditions are met.
Days 1–180 — Watch Period
The 180-day clock is running. The ITC remains valid as long as payment is made before Day 180. No action required during this period unless payment is clearly not forthcoming.
Day 181 — Reversal Mandatory
If unpaid: The ITC must be reversed in the GSTR-3B for the month in which Day 181 falls. Interest at 18% p.a. under Section 50(1) runs from the date of original ITC claim to the date of reversal.
Post-Reversal — Payment Made
Re-claim allowed: On making payment to the supplier (even after Day 181), the ITC can be re-claimed in the GSTR-3B of the period in which payment is made. No fresh interest applies on re-credit.

3. Computation: Full vs Partial Payment

Rule 37 addresses both full non-payment and partial payment situations. Where only a portion of the invoice is paid within 180 days, the reversal is proportionate to the unpaid amount.

📖 Rule 37(1) — Proportionate Reversal Formula

Where the registered person has paid only a part of the invoice value, the ITC to be reversed is computed as:

ITC Reversal = (ITC on invoice) × (Unpaid value ÷ Total invoice value)

Read the full text of Rule 37 in the CGST Rules →

🔢 Worked Example — Partial Payment Scenario

Buyer pays 60% of an invoice but the remaining 40% is outstanding at Day 181

Invoice value: ₹10,00,000 + GST at 18% = ₹1,80,000. Total payable: ₹11,80,000.

ITC claimed: ₹1,80,000 (in Month 1 GSTR-3B).

Amount paid within 180 days: ₹7,08,000 (60% of ₹11,80,000).

Amount unpaid at Day 181: ₹4,72,000 (40% of ₹11,80,000).

ITC to reverse: ₹1,80,000 × 40% = ₹72,000

Interest at 18% p.a. on ₹72,000 from date of ITC claim to date of reversal (say 6 months): ₹72,000 × 18% × 6/12 = ₹6,480

ITC retained (on paid portion): ₹1,08,000 — no reversal required on this.

When the remaining ₹4,72,000 is eventually paid, ₹72,000 ITC can be re-claimed in that month’s GSTR-3B.

4. Rule 37A: Supplier Non-Filing — A Parallel Track

Rule 37A was introduced by CBIC Notification No. 26/2022-CT to address a different but related problem — what happens when the supplier does not file GSTR-3B, even though the buyer has already paid the supplier?

Under Rule 37A, if the supplier has filed GSTR-1 (invoice visible in GSTR-2B on the GST portal) but has not filed GSTR-3B for the relevant period, the buyer must reverse the ITC if the supplier’s GSTR-3B remains unfiled by 30th September of the financial year following the year of the invoice.

ParameterRule 37 (Buyer Non-Payment)Rule 37A (Supplier Non-Filing)
Trigger Buyer has not paid supplier within 180 days Supplier has filed GSTR-1 but not GSTR-3B
Deadline for reversal GSTR-3B for the month in which Day 181 falls GSTR-3B for the month of September of the FY following the invoice FY
Interest rate 18% p.a. under Section 50(1) 18% p.a. under Section 50(1)
Re-claim possible? Yes — on payment to supplier Yes — once supplier files GSTR-3B and pays tax
Buyer’s control Full — buyer can pay supplier to avoid reversal None — buyer cannot force supplier to file return
🚨 Rule 37A — The Hardship on Buyers

Rule 37A places a significant compliance burden on innocent buyers. A buyer who has paid their supplier in full and claimed ITC correctly can still be forced to reverse that ITC — and pay 18% interest under Section 50(1) — simply because their supplier failed to file a return. The only remedy is to pursue the supplier to file, or absorb the cost and re-claim once the supplier eventually files.

5. Practical Difficulties Under Rule 37

Rule 37 is straightforward in concept but operationally demanding. Below are the most common real-world challenges businesses and their CAs face when navigating GST compliance under this rule.

Difficulty 1

Tracking 180-Day Deadlines Across Hundreds of Invoices

A medium-sized business can have hundreds of purchase invoices per month, each with its own 180-day clock. Manually tracking which invoices are approaching the deadline is error-prone and frequently missed until a notice arrives.
Build a rolling “ITC aging tracker” in Excel or your ERP — flag all invoices where payment + 180 days is within the next 30 days. Many GST software platforms now include Rule 37 monitoring dashboards. Integrate payment date capture into your accounts payable workflow.
Difficulty 2

Payment Withheld Due to Defective Goods or Commercial Disputes

A buyer may legitimately withhold payment because goods received were defective or services were substandard. The GST law, however, does not recognise the reason for non-payment — if 180 days have passed, the reversal is mandatory regardless of commercial justification.
Where goods are defective and payment is being withheld, request the supplier to issue a credit note immediately. A valid credit note reduces the invoice value (and therefore the ITC claimable), eliminating the Rule 37 exposure on the disputed amount. Document all disputes formally in writing.
Difficulty 3

Partial Payments and Multiple Tranches Against Single Invoices

Large contracts often involve invoices paid over multiple instalments. Each instalment must be mapped against the total invoice value to compute the outstanding percentage. Many businesses fail to do this mapping correctly, leading to under-reversal or over-reversal.
Maintain a payment-to-invoice mapping ledger. For each purchase invoice, track: total invoice value including GST, amount paid to date, outstanding balance, and the 180-day deadline date. Reconcile this against the ITC claimed and calculate proportionate reversal only on the unpaid portion per Rule 37(1).
Difficulty 4

Credit Notes Received After ITC Is Claimed

A supplier issues a credit note after the buyer has already claimed full ITC on the original invoice. If the net amount payable (after credit note) remains unpaid beyond 180 days, the computation becomes complex.
When a credit note is received, immediately reduce the ITC claimed in the current period’s GSTR-3B (Table 4(B)(2)). The 180-day clock should then be computed on the net payable amount after the credit note. Maintain a clear audit trail linking each credit note to its original invoice.
Difficulty 5

Non-Monetary Consideration / Barter Transactions

Where the consideration for a supply is non-monetary — for example, goods supplied in exchange for advertising services — the concept of “payment to supplier” becomes legally uncertain. No CBIC clarification exists on this as of April 2026.
The safer position is to treat the exchange as completed (and Rule 37 satisfied) only when the corresponding outward supply is made and the supplier’s receivable is extinguished. Document the commercial arrangement carefully. Seek an advance ruling if the transaction value is material.
Difficulty 6

Supplier Goes Insolvent or Untraceable Before Payment

A supplier goes into insolvency proceedings (CIRP under IBC) or becomes uncontactable after delivering goods. The buyer cannot make payment because the supplier’s bank accounts are frozen. The 180-day clock runs regardless.
Where the supplier is under CIRP, file a claim with the Resolution Professional as a creditor. Reverse the ITC and interest at Day 181 to remain compliant. Once the proceedings resolve and valid payment instructions are available, make the payment and re-claim the ITC.
Difficulty 7

Determining Whether “Payment” Includes TDS / TCS Deducted

Where TDS under Income Tax or TCS under GST is deducted at source, the net payment to the supplier is less than the full invoice value. The Act does not explicitly define whether TDS/TCS deducted counts as “payment” for Rule 37 purposes.
The general practitioner position is that TDS/TCS deducted at source should be treated as payment made on behalf of the supplier (since the deducted amount is deposited to the government and credited to the supplier). The net payment plus TDS/TCS should therefore equal the full invoice value, satisfying Rule 37.

6. Interest on Rule 37 Reversal: Recap

As covered in detail in Part 4 of this series, Rule 37 reversals attract interest at 18% p.a. under Section 50(1) — not 24%. This is because the reversal is treated as a delayed discharge of tax liability rather than a wrongful ITC claim.

EventInterest RateInterest Period
Rule 37 reversal (buyer non-payment beyond 180 days) 18% p.a. From date ITC was originally availed to date of reversal in GSTR-3B
Rule 37A reversal (supplier non-filing) 18% p.a. From date ITC was originally availed to date of reversal
ITC re-claimed after reversal (post payment / post supplier filing) Nil No fresh interest on re-credited ITC
Interest already paid on reversal period Not refundable The interest cost of the delay is a sunk cost even after re-claim
💡 Planning Tip — Minimise Interest Cost

If you know a payment will not be made within 180 days, consider reversing the ITC proactively before Day 181. This reduces the interest period and demonstrates voluntary compliance. The ITC can still be re-claimed once payment is made, with no interest on the re-credit.

7. How to Report Rule 37 Reversals in GSTR-3B

Table in GSTR-3BWhat to Enter
Table 4(B)(1) ITC reversed as per Rule 42 & 43 — for capital goods mixed use (not Rule 37)
Table 4(B)(2) ITC reversed on account of Rule 37 (non-payment to supplier within 180 days) and Rule 37A (supplier non-filing) — report the reversal amount here
Table 4(A)(5) When re-claiming ITC after payment to supplier post-reversal — enter re-claim in the “All other ITC” row of Table 4(A)
Table 5.1 Interest payable on the reversal — computed separately and paid in cash through the electronic cash ledger on gst.gov.in
⚠️ Common Filing Error

Many businesses mistakenly report Rule 37 reversals in Table 4(B)(1) — which is meant for Rule 42/43 proportionate reversals — instead of Table 4(B)(2). While the net effect on ITC is the same, incorrect table allocation can lead to discrepancies in GSTR-9 reconciliation and trigger scrutiny queries. Always use Table 4(B)(2) specifically for Rule 37 and Rule 37A reversals.

8. Quick Reference: Rule 37 & Rule 37A at a Glance

ParameterPosition Under Rule 37 / Rule 37A
Statutory basisProviso to Section 16(2)(b) → Rule 37; Rule 37A (Notification 26/2022-CT)
Rule 37 triggerNon-payment of invoice value (value + GST) to supplier within 180 days of invoice date
Rule 37A triggerSupplier files GSTR-1 but not GSTR-3B by 30th September of following FY
Reversal deadline — Rule 37GSTR-3B for the month in which the 181st day falls
Reversal deadline — Rule 37AGSTR-3B for October (due 20th November) of the following FY
Partial paymentProportionate reversal — ITC × (unpaid value ÷ total invoice value)
Interest rate18% p.a. under Section 50(1) — from date of ITC claim to date of reversal
Interest payment modeCash only — electronic cash ledger via gst.gov.in; ITC cannot be used
Re-claim of ITCYes — in GSTR-3B of the month payment is made (Rule 37) or supplier files GSTR-3B (Rule 37A)
GSTR-3B table for reversalTable 4(B)(2)
GSTR-3B table for re-claimTable 4(A)(5) — All other ITC

Frequently Asked Questions

The 180-day rule, implemented through the proviso to Section 16(2)(b) and Rule 37 of the CGST Rules, requires a registered person to reverse the ITC claimed on any invoice if the total invoice value (goods or services value plus GST) has not been paid to the supplier within 180 days of the date of the invoice. The reversal must be made in the GSTR-3B for the month in which the 181st day falls, along with interest at 18% p.a. under Section 50(1).
Yes. Once the payment is made to the supplier — even after the 180-day window has expired and the reversal has been made — the ITC can be re-claimed in the GSTR-3B for the month in which the payment is made. No fresh interest applies on the re-credited amount. However, the interest already paid for the period of the reversal is not refunded — it remains a cost of the delayed payment.
Rule 37 deals with the buyer’s own non-payment to the supplier within 180 days. Rule 37A, introduced in 2022, addresses a separate situation: where the supplier has filed GSTR-1 (invoice in GSTR-2B) but has not filed GSTR-3B (tax not paid to government). In this case, the buyer must reverse the ITC if the supplier’s GSTR-3B remains unfiled by 30th September of the following financial year. The critical difference is that Rule 37A can trigger a reversal even when the buyer has paid the supplier in full.
GST law does not recognise the reason for non-payment when applying Rule 37 — if 180 days have elapsed without full payment, the reversal is mandatory regardless of why payment was withheld. The recommended approach for defective goods is to ask the supplier to issue a credit note, which reduces the payable invoice value and eliminates the Rule 37 exposure on the disputed amount. If the supplier refuses to issue a credit note, the ITC on the disputed portion must still be reversed at Day 181.
No. Rule 37(1) requires proportionate reversal. If only a part of the invoice value is paid within 180 days, only the ITC proportionate to the paid amount is protected. The ITC corresponding to the unpaid balance must be reversed with interest at 18% p.a. The reversed ITC can be re-claimed once the remaining balance is paid.
The most reliable approach is an ITC aging tracker — a spreadsheet or ERP report that lists all purchase invoices, their dates, amounts, payment status, and the 180-day deadline date. The tracker should flag invoices where the deadline is within the next 30–45 days. Most modern accounting software now includes built-in Rule 37 monitoring reports. CAs should make this tracker review a standard part of the monthly GSTR-3B preparation checklist.
📚 Continue the Series
Disclaimer: This article is prepared by the TaxRoutine Research Team for general informational purposes only. It does not constitute legal or professional tax advice. GST law including Rule 37 and Rule 37A has been subject to amendments, notifications, and CBIC clarifications. Readers are advised to consult a qualified GST practitioner. TaxRoutine is not liable for any consequences arising from reliance on this content.

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