Content authored by practitioners with experience at Amazon India, Intuit QuickBooks, and the Tata Group. Meet the team →
Auto OEMs frequently pay Tier-1 and Tier-2 supplier invoices in tranches — a portion at the acceptance stage and the balance withheld for retention, quality holds, or aggregated month-end release. When a portion remains unpaid at Day 181 from the invoice date, many finance teams reverse the entire ITC on the invoice, treating the Second Proviso to Section 16(2) as an all-or-nothing switch. This inflates the reversal amount by the ratio of paid-to-total and creates a working-capital hit that is legally unnecessary.
Compute the unpaid portion of every open invoice at Day 181. Apply the invoice-level tax rate to only that unpaid portion to derive the ITC amount to reverse. Report the proportionate reversal in Table 4(B)(2) of GSTR-3B for the return period of the breach. When the buyer subsequently pays the balance, re-avail the ITC in Table 4(A)(5) with the reference in Table 4(D)(1). Match the re-availment to the delta payment (not the invoice) so the register stays tied to bank movements.
Ageing counter starts at invoice date, not GRN date or acceptance date; 180-day window applied to net-of-credit-note unpaid balance; retention amounts tagged and excluded from the reversal test unless they exceed the contractual warranty release window; buyer-issued debit notes ignored for reversal calculation unless mirrored by a supplier credit note; re-availment triggered by bank debit UTR, not by AP payment run.
Proportionate-reversal register showing invoice number, invoice date, invoice value, GST amount, paid-to-date, unpaid balance at Day 181, tax rate, proportionate ITC to reverse, Table 4(B)(2) reporting line, re-availment status, re-availment UTR, and Table 4(A)(5) reporting line. Register reconciles to GSTR-3B Table 4 on both the reversal and re-availment side for every return period.
The Second Proviso to Section 16(2) of the CGST Act is one of the most misapplied provisions in auto-component ITC reconciliation. The rule itself is simple: if a buyer does not pay the supplier the value plus tax within 180 days from the date of the invoice, the input tax credit availed on that invoice is added back to the buyer’s output tax liability, with interest. Where finance teams go wrong is on the amount — the reversal is proportionate to the unpaid portion, not the full ITC on the invoice. A payment that clears 63% of an invoice at Day 175 does not trigger reversal on 100% of the ITC at Day 181; it triggers reversal on the 37% that remains unpaid.
This article is most relevant for AP managers, GST reconciliation leads, and CFOs at Tier-1 and Tier-2 auto-component suppliers and OEM buyers where invoice-level tranche payments are the norm.
The reconciliation in one paragraph
For every open invoice at Day 181 from the invoice date, compute the unpaid amount net of any supplier-issued credit notes. Apply the invoice-level GST rate to that unpaid amount to derive the ITC to reverse. Report the proportionate reversal in Table 4(B)(2) of GSTR-3B in the return period of the breach. When the buyer subsequently settles the balance, re-avail the ITC in Table 4(A)(5) of GSTR-3B with a reference in Table 4(D)(1), matched to the bank debit UTR of the delta payment. Maintain a proportionate-reversal register that reconciles to Table 4 on both the reversal and re-availment side.
What the partial-payment ITC clawback looks like in India — auto-component realities
Tranche payments are structural in auto-component supply chains for reasons that have nothing to do with dispute. Bosch India ships a batch of high-pressure common-rail injectors to Maruti Suzuki against a ₹35 lakh tax invoice. Maruti Suzuki’s AP process releases 63% of the invoice value inside 45 days — the “clean” portion — and holds the remainder in one of several buckets: a 5% retention against warranty defects, a 7% quality hold pending line trial results, and a balance awaiting a subsequent debit note for a small quantity of parts that were rejected on inbound inspection.
At Day 181, the 5% retention is still live, the quality hold has released, and the rejection-debit portion has been resolved via a Section 34 credit note from Bosch India that reduces the effective invoice value. The buyer AP team sees an “unpaid” balance on their books and has to make a call: reverse the full ITC on the original invoice, or reverse only the portion attributable to the truly unpaid amount at Day 181.
The same pattern shows up across the supply chain. Motherson Sumi shipping instrument clusters to Hyundai India, Bharat Forge shipping crankshaft forgings to Tata Motors, Sundram Fasteners shipping fastener kits to Ashok Leyland, Endurance Technologies shipping suspension components to Mahindra & Mahindra, Sona BLW shipping driveline sub-assemblies to Ashok Leyland, Uno Minda shipping switch assemblies to Maruti Suzuki, Rico Auto shipping die-cast housings to Tata Motors, Amara Raja Batteries shipping automotive batteries to multiple OEMs, ZF India shipping steering systems to Mahindra & Mahindra — the payment structures differ in shape (retention vs milestone vs holdback for supplier development amortisation) but the reconciliation problem is identical: how much ITC is genuinely at risk under the Second Proviso when a portion of consideration remains unpaid.
The default answer many finance teams give — “reverse everything and re-avail when the balance clears” — is a reading of the statute that has been overtaken by Rule 37 as amended in September 2022, and by the CBIC’s own clarification in Circular 170/02/2022-GST.
The regulatory overlay — Section 16(2), Rule 37, Circular 170, and case law
The statutory chain has four moving parts, and reading any one of them in isolation is what produces the naive full-reversal interpretation.
Second Proviso to Section 16(2) CGST Act — the source of the obligation. Where the recipient fails to pay the supplier the amount of the value plus tax within 180 days from the date of the invoice, an amount equal to the input tax credit availed shall be added to the output tax liability along with interest. Read alone, the phrase “input tax credit availed” seems to point at the whole ITC on the invoice.
Third Proviso to Section 16(2) — the re-availment right. The recipient shall be entitled to re-avail the credit on payment being made to the supplier. This confirms the reversal is not permanent; it is a timing mechanism, not a punishment.
Rule 37 of the CGST Rules — the procedural anchor. Rule 37 as substituted by Notification 19/2022-CT effective 1 October 2022 requires the recipient to reverse “an amount equal to the input tax credit availed in respect of such supply proportionate to the amount not paid to the supplier”. The word “proportionate” is the statutory basis for the pro-rata reading. Before September 2022 the language was less explicit, and this is part of why the naive interpretation persists in older process notes.
CBIC Circular 170/02/2022-GST dated 6 July 2022 — the reporting clarification. Reversals under Rule 37 are to be reported in Table 4(B)(2) of GSTR-3B. Re-availment on subsequent payment is to be reported in Table 4(A)(5) with a reference in Table 4(D)(1). The circular treats the reversal as a self-executed line entry, not a departmental proceeding, so the buyer’s own registers must be able to prove the proportionate amount.
Suncraft Energy Pvt Ltd vs Assistant Commissioner (Calcutta High Court, December 2023) — the case-law reinforcement. Suncraft Energy addressed a different fact pattern — ITC denial to a recipient because the supplier had not paid its own output tax — but the reasoning is directly applicable. The court held that ITC entitlement is tied to the recipient’s compliance with the documentary conditions of Section 16(2), and that reversals cannot be mechanical or disproportionate. Several tribunals and High Courts have since applied the same logic to Rule 37 disputes, reinforcing that the proportionate reversal reading is the intended one.
Read together, the four sources produce an unambiguous position: the reversal amount equals the tax rate applied to the unpaid portion of the invoice at Day 181, and re-availment is available on the delta payment.
A worked example — Bosch India to Maruti Suzuki, ₹35 lakh invoice
The numbers below are illustrative and are used to expose the difference between the naive and correct reversal calculations. They are not drawn from any specific transaction.
Bosch India raises Tax Invoice BSC/26-27/00218 dated 1 January 2026 to Maruti Suzuki for ₹35,00,000 plus 18% IGST of ₹6,30,000, totalling ₹41,30,000. Maruti Suzuki avails the ₹6,30,000 ITC in the January 2026 GSTR-3B against the auto-populated GSTR-2B entry.
Between invoice date and Day 180 (30 June 2026), Maruti Suzuki makes two payments and one adjustment:
| Event | Date | Amount | Cumulative paid | Balance outstanding |
|---|---|---|---|---|
| Payment 1 — clean portion release | 15 February 2026 | ₹22,00,000 | ₹22,00,000 | ₹19,30,000 |
| Section 34 credit note from Bosch India — inbound rejection settlement | 10 April 2026 | ₹4,00,000 credit | Effective invoice value ₹37,30,000; balance ₹15,30,000 | ₹15,30,000 |
| Payment 2 — quality hold release | 20 May 2026 | ₹2,30,000 | ₹24,30,000 | ₹13,00,000 |
At Day 181 (1 July 2026), the unpaid balance on the effective invoice value of ₹37,30,000 is ₹13,00,000. Of this, ₹1,86,500 is a 5% retention captured explicitly in the contract; ₹11,13,500 is unpaid consideration outside the retention envelope.
The naive calculation (wrong)
Full ITC reversal on the invoice:
- ITC availed: ₹6,30,000
- Reversed at Day 181: ₹6,30,000
- Interest at 18% per annum for the period from ITC availment until reversal report: additional several thousand rupees
The naive calculation reverses 100% of the ITC even though only 34.8% of the effective invoice value is unpaid. It also reverses the ITC attributable to the ₹22,00,000 already paid, which serves no statutory purpose.
The correct calculation (Rule 37 proportionate)
Unpaid balance at Day 181, net of credit note, applied to the tax rate:
- Unpaid balance: ₹13,00,000
- Proportionate ITC to reverse: ₹13,00,000 × 18% = ₹2,34,000
- Interest on ₹2,34,000 from ITC availment until reversal report
The proportionate reversal is ₹2,34,000 against the naive ₹6,30,000. The difference — ₹3,96,000 — is working capital that stays with the buyer instead of being pushed into the government’s cash ledger for a period that could easily run six to twelve months before the balance is settled and re-availment is claimed.
A more conservative auto-component AP team might additionally exclude the ₹1,86,500 retention from the reversal test on the basis that retention is contractually withheld and not defaulted consideration — bringing the reversal down further to ₹11,13,500 × 18% = ₹2,00,430. Whether to take that position depends on the strength of the retention documentation and the risk appetite of the tax function.
Re-availment on the delta payment
Assume Maruti Suzuki releases the balance ₹13,00,000 in September 2026 following warranty period closure. In the September 2026 GSTR-3B:
- Re-avail ₹2,34,000 in Table 4(A)(5)
- Reference the re-availment in Table 4(D)(1)
- Reconcile the entry to the bank debit UTR of the September payment
The reversal and re-availment together are net-neutral over the two return periods — the buyer has effectively paid interest on ₹2,34,000 for the period between availment and re-availment, which is a much smaller cash cost than paying interest on ₹6,30,000 for the same period.
Common reconciliation breakages
Treating GRN date or acceptance date as the ageing start. The Second Proviso and Rule 37 both anchor the 180-day counter to the date of the invoice. AP teams that start the counter at goods receipt note or line-acceptance date understate exposure on early invoices and overstate exposure on late ones. The invoice date is the only defensible anchor.
Ignoring supplier credit notes when computing the unpaid balance. A Section 34 credit note issued by the supplier reduces the effective invoice value. If the credit note is not carried into the ageing register, the buyer over-reverses because the “unpaid” balance shown in the register includes an amount the supplier is no longer claiming.
Applying the reversal to the wrong tax rate. Auto-component invoices carry different rates depending on HSN — 28% for some passenger vehicle assemblies, 18% for most components and services, 5% for certain EV parts under the current schedule. Applying a blanket 18% rate to the unpaid balance for reversal purposes creates small but persistent errors that add up across hundreds of invoices per month.
Confusing buyer debit notes with supplier credit notes. A debit note raised by the buyer for rejection or price adjustment does not reduce the invoice value for Rule 37 purposes unless the supplier accepts it by issuing a matching Section 34 credit note. Many AP systems reduce the payable on the debit note, but the tax invoice remains at the original value until the supplier credit note is issued. This creates a mismatch between the payable ledger and the reversal register.
Ignoring retention money in the register. Retention is a category of its own — contractually withheld consideration against warranty performance. Best practice is to tag retention amounts separately in the reversal register so that (a) they can be excluded from the reversal test where the contract makes the retention pattern clear, and (b) if the retention itself overruns the contractual release window, it can be reintroduced into the reversal calculation. See our companion article on 5% retention debit is not a short-payment for the retention-specific treatment.
Missing the re-availment UTR link. Re-availment in Table 4(A)(5) must be traceable to a specific bank debit — the payment that cleared the balance. AP teams that re-avail on the basis of the payment run date rather than the bank debit UTR lose the audit trail. In a GST audit, the department will look for the UTR-linked re-availment, not the AP run.
One-time reversal register at year-end. Rule 37 requires reporting in Table 4(B)(2) in the return period of the breach — meaning monthly, not annually. Teams that build the reversal register at year-end miss the monthly reporting obligation and end up reporting reversals late, attracting interest under Section 50.
Confusing the 180-day counter with the Section 43B(h) 45-day MSME counter. These are entirely different obligations. Section 43B(h) is an income-tax disallowance for payments to MSME suppliers not made within 15 or 45 days; the Second Proviso to Section 16(2) is a GST ITC reversal for payments to any supplier not made within 180 days. Both counters run in parallel for MSME auto-component suppliers, and both need separate registers.
How a reconciliation platform handles this
The registers described above look simple at low volume — a spreadsheet of open invoices, an ageing bucket at Day 181, a formula for proportionate reversal. At auto-component AP volume, where a Tier-1 supplier may have 3,000-8,000 open invoices at any time across a handful of OEM buyers, the spreadsheet approach breaks in three specific ways.
The first is the credit-note linkage. Every supplier credit note must be tied back to the original invoice number that it reduces, and the effective invoice value in the ageing register must be updated the moment the credit note is accepted. Manual linkage misses 5-10% of credit notes at any given month-end.
The second is the bank UTR link on the re-availment side. Re-availment requires a specific bank debit reference — not an AP payment run identifier. When the buyer runs a batch payment covering fifty invoices, the register needs to allocate the batch UTR back to each invoice’s unpaid balance. This is a one-to-many allocation problem that spreadsheets handle badly.
The third is the Table 4 reconciliation. Every month, the total of Table 4(B)(2) in GSTR-3B needs to tie to the sum of the reversal lines in the register, and the total of Table 4(A)(5) needs to tie to the sum of the re-availment lines. Where the totals differ, the difference has to be attributable to a specific invoice — otherwise the register is decorative rather than defensible.
Reconciliation software India purpose-built for GST workflows carries the invoice-credit note linkage, the UTR-to-invoice allocation, and the Table 4 tie-out as first-class primitives. The same platform handles the GST reconciliation software workload of matching GSTR-2B against the purchase register, so the reversal register sits on top of a data model that is already tracking every invoice by GSTIN, invoice number, invoice date, and tax rate. Adding the 180-day counter and the unpaid-balance calculation to that model is a matter of layering — not a separate system.
The output the platform produces is the same output described in the knowledge card above: a proportionate-reversal register with invoice-level detail, Table 4(B)(2) and Table 4(A)(5) reporting lines, re-availment UTRs, and a monthly tie-out to GSTR-3B. The register survives a departmental audit because every line is traceable to an invoice, a credit note, a payment date, and a bank UTR — the evidence chain that Suncraft Energy and the surrounding case law establishes as the minimum standard for defensible ITC positions.
Content authored by practitioners with experience at Amazon India, Intuit QuickBooks, and the Tata Group. Meet the team →
- ▸ Central Goods and Services Tax Act 2017 — Section 16(2), Second Proviso — Second Proviso to Section 16(2): where a recipient fails to pay the supplier of goods or services the value plus tax within 180 days from the date of the invoice, an amount equal to the input tax credit availed shall be added to output tax liability along with interest — with re-availment permitted on subsequent payment (Third Proviso)
- ▸ CGST Rules 2017 — Rule 37 — Rule 37 (as amended by Notification 19/2022-CT dated 28 September 2022) prescribes the procedure for reversal of ITC where consideration is not paid within 180 days — reversal is proportionate to the unpaid portion of the invoice
- ▸ CBIC Circular 170/02/2022-GST — Clarification on Table 4 of GSTR-3B — reversal under Rule 37 to be reported in Table 4(B)(2), and re-availment on subsequent payment reported in Table 4(A)(5) with a reference in Table 4(D)(1)
- ▸ Suncraft Energy Pvt Ltd vs Assistant Commissioner (Calcutta HC 2023) — Calcutta High Court held that ITC cannot be denied to a recipient purely on the basis of supplier default when the recipient has met the documentary conditions of Section 16(2) — reinforcing that the buyer's ITC entitlement is tied to their own compliance, and that reversals must be proportionate and evidence-based