Correct Approach for ITC Reversal Under Rule 37 When Rule 42 Is Also Applicable

Businesses frequently deal with common input tax credit (ITC) used for both taxable and exempt outward supplies. In such cases, Rule 42 of the CGST Rules requires proportionate reversal of common ITC attributable to exempt supplies. At the same time, Rule 37 mandates ITC reversal if the assessee does not pay the supplier within 180 days from the invoice date.

Where both rules apply on the same inward supply, confusion often arises on how much ITC should be reversed and how to avoid reversing the same ITC twice. This write-up explains a practical and legally sound method to compute ITC reversal under Rule 37 in situations where part of the ITC has already been reversed under Rule 42.

The focus is on:

Understanding the scope and mechanics of Rule 37 and Rule 42
Demonstrating the correct computation methodology with numbers
Highlighting common mistakes leading to double reversal of ITC
Clarifying the treatment of TDS/TCS for the purpose of Rule 37

1. Scope and Objective of This Discussion

1.1 Issues Covered

This analysis is centred around:

When and how Rule 37 is triggered for non-payment of consideration to suppliers beyond 180 days
How to compute the amount to be reversed under Rule 37 when a part of ITC on the same invoice has already been reversed under Rule 42
How to factor in TDS while determining payment to suppliers
Transactions outside the ambit of Rule 37

1.2 Key Principle

Even if Rule 42 already applies, the assessee is not required to reverse the full ITC again under Rule 37.

The correct approach is:

Compute the amount to be reversed under Rule 37 on the full GST shown in the invoice, and

Reduce from this figure the ITC that has already been reversed under Rule 42 on the same supply.

This ensures there is no duplication of ITC reversal and compliance is consistent with both rules.

2. Understanding Rule 37 – Reversal for Non-Payment Within 180 Days

2.1 When Does Rule 37 Apply?

Rule 37 becomes operative when all of the following are satisfied:

The assessee has availed ITC on inward supplies of goods, services or both in GSTR-3B.
Such supplies are not subject to tax under reverse charge (i.e., tax is payable by supplier, not recipient).
The assessee fails to pay the supplier, partly or fully, the value of the supply plus tax within 180 days from the invoice date.

Once this 180-day period expires, the assessee must pay back or reverse the relevant portion of ITC in the GSTR-3B of the period immediately following expiry of 180 days, along with interest under section 50.

2.2 Proportionate Reversal – Not Always 100%

Rule 37 works on a proportionate basis:

Only the ITC corresponding to the unpaid portion of invoice value (value + tax) is required to be reversed.
If part payment has been made, ITC attributable to the amount paid remains admissible.

Formula (Conceptual)

Allowable ITC = (GST as per invoice / Invoice value) × (Amount actually paid, including eligible TDS)

ITC to be reversed = (GST as per invoice / Invoice value) × (Unpaid amount)

2.3 Treatment of Subsequent Payment

If the assessee later pays the supplier the invoice value plus tax, Rule 37(2) allows re-availment of the ITC earlier reversed under Rule 37. The time limit under section 16(4) does not apply to such re-availment as clarified by Rule 37(4).

3. Transactions Not Covered Under Rule 37

Rule 37 does not apply to every ITC item. The following are outside its scope:

ITC reversal under Rule 37 when Rule 42 is already applied: How to prevent double reversal