GSTR-2B vs purchase register — reconciling input tax credit

Input tax credit is where GST quietly leaks money. You've paid the tax to your supplier, you've booked the purchase, and you assume the credit is yours. But under the current law, your ITC is only as safe as its match to GSTR-2B — the government's record of what your suppliers actually reported. If an invoice isn't in your 2B, the credit isn't yours, no matter what your books say. Reconciling the two, every month, is the single most valuable routine in a GST function.

What GSTR-2B actually is

GSTR-2B is a static, auto-drafted input tax credit statement generated for you each month (around the 14th) from what your suppliers filed in their GSTR-1, IFF, GSTR-5 and GSTR-6. “Static” is the key word: once generated for a period, it doesn't change — so it's a stable basis to claim against. It also tells you, invoice by invoice, whether the credit is available or not available, and why (place of supply, time-barred, reverse charge, and so on).

2B vs 2A — why the switch matters

GSTR-2A is the older, dynamic statement: it keeps changing as suppliers file and amend, so you can never “close” a period against it. GSTR-2B is the snapshot you reconcile and claim on. In short: 2A is for tracking, 2B is for claiming.

The reconciliation, invoice by invoice

The job is to match your purchase register against 2B at the invoice level — GSTIN, invoice number, taxable value and tax — and sort every entry into one of four buckets. What you do next depends entirely on which bucket it lands in.

The rule that makes this non-negotiable

Since Section 16(2)(aa) came into force, ITC is available only if the invoice has been furnished by your supplier and appears in your GSTR-2B. Rule 36(4), which once allowed a small provisional credit for unmatched invoices, has been tightened to the same 100% standard. Put plainly: no invoice in 2B, no credit — the “in books, not in 2B” bucket is money you cannot claim until the supplier files.

Why invoices don't match

Most mismatches are the supplier's doing, not yours:

• Wrong GSTIN — the supplier billed a different registration of your group, so it lands in someone else's 2B.
• Wrong period — they filed the invoice in a later month, so it shows up in a 2B you've already closed.
• Not filed at all — the supplier hasn't filed GSTR-1 yet (or is a defaulter).
• B2B booked as B2C — the supplier reported it without your GSTIN, so it never reaches your 2B.
• Value or invoice-number differences — typos, rounding, or a credit note the supplier issued that you haven't booked.

Chasing the supplier

The reconciliation only pays off if the follow-up is systematic. Turn the “in books, not in 2B” bucket into a supplier-wise list, send it every month, and — where the amounts are material — make the next payment conditional on the invoice appearing in your 2B. Under Section 16(2)(c) the supplier must also actually pay the tax, so a supplier who files but doesn't pay is still a risk worth tracking.

Doing it at scale

For a handful of invoices, a VLOOKUP does the job. For hundreds or thousands a month across multiple GSTINs, manual matching breaks down — and that's exactly where the credit leaks. The work is mechanical and rules-based, which makes it a natural fit for automation: pull 2B and the purchase register, match on GSTIN and invoice, and output the four buckets with a supplier follow-up list.

The principle

Input tax credit isn't what your books say you're owed — it's what your suppliers reported and paid. Reconcile GSTR-2B to your purchase register every month, work the four buckets, chase the gaps before the November deadline, and the credit you claim is credit that survives a notice. Skip it, and you find out what you lost only when the department does.