GSTR-1, 2B And 3B: How They Actually Fit Together

The three returns, in the order they matter

Most filing confusion comes from treating GSTR-1, 2B and 3B as three separate chores. They are one chain: what you declared, what your suppliers declared about you, and what you actually pay after netting the two.

Read that table twice and the sequencing becomes obvious: 2B is not something you prepare. It is a verdict handed to you, assembled from what other people filed about you. Your only lever is chasing them before the window closes.

GSTR-1 — what you declare

GSTR-1 is your outward supply statement: every B2B invoice line by line, B2C above the threshold, credit and debit notes, exports, and advances. Monthly filers submit by the 11th; QRMP filers file quarterly but can push invoices monthly through IFF so their customers are not left waiting for credit.

The part firms underestimate: GSTR-1 is a customer-facing document. An invoice you forget, or key with the wrong GSTIN, does not just misstate your turnover — it silently denies your customer their input credit, and you will hear about it from their accounts team long before you hear about it from the department.

GSTR-2B — what you can claim

GSTR-2B is a static, auto-drafted statement generated on the 14th. Static matters: unlike the older 2A, it does not keep shifting under you. What it shows on the 14th is what you may claim for that period, full stop.

So the reconciliation question is never “what did I buy?” It is “what did my suppliers say they sold me, and does it match my purchase register?” Four outcomes:

• In books, in 2B — claim it, nothing to do.
• In books, not in 2B — your supplier has not filed, or filed against the wrong GSTIN. Chase them; do not claim it.
• In 2B, not in books — a bill you never recorded, or one addressed to you in error. Find the invoice before you claim.
• In both, different amounts — usually a rate or a rounding difference; sometimes a credit note only one side has recorded.

Where IMS changed things

The Invoice Management System added an action step that did not exist before. Invoices your suppliers file now arrive in a place where you must accept, reject, or leave them pending — and what you do there flows into your 2B.

Practically, this converts reconciliation from a monthly cleanup into a rolling habit. Leaving everything pending is not neutral; it defers credit. Accepting everything blindly imports your suppliers’ mistakes into your own return.

GSTR-3B — what you pay

3B is the summary where output tax from your GSTR-1 meets input credit permitted by your 2B, and the difference is paid in cash. It is filed by the 20th for monthly filers.

Because it is a summary, 3B hides the detail that caused it. A wrong number here is almost never a 3B problem — it is a GSTR-1 problem or a 2B reconciliation problem that arrived in the summary unchallenged.

Where it breaks in practice

In a working practice, filing rarely fails on the law. It fails on the plumbing:

1. The books are not current. Bank entry sits half done, so purchases are missing and 2B looks wrong when it is not.
2. Tax is decided at filing time, not entry time. Someone reconstructs CGST/SGST versus IGST from memory at the 18th, and place of supply gets guessed.
3. Data is re-typed into a portal sheet. Every re-keying is a fresh chance to transpose a GSTIN or drop a zero.
4. Suppliers are chased late. The mismatch is found on the 19th, when nobody can fix anything before the 20th.
5. Amendments are untracked. Last quarter’s fix is invisible this quarter, and the same invoice gets corrected twice.

Every one of those is a bookkeeping failure wearing a compliance costume.

The pre-filing checklist

Before GSTR-1 goes out:

• Every sales invoice for the period is recorded, including credit notes.
• Counterparty GSTINs validate, and place of supply is right on every inter-state line.
• Intra-state lines carry CGST + SGST; inter-state carry IGST. Never both, never mixed.
• Invoice numbering is unbroken — gaps invite questions.
• HSN summary matches the item master.

Before 3B goes out:

• 2B has been reconciled and IMS actions taken, not left pending.
• ITC not appearing in 2B is excluded, with the supplier chased in writing.
• Reverse-charge liabilities are recognised.
• The trial balance ties — if the books do not balance, the return is a guess.

Doing it from the books instead

Everything above collapses if tax is captured where the transaction happens rather than reconstructed at quarter-end. That is the whole design argument: a return should be a report of what you already recorded, not a second data-entry exercise.

In Autobooks, the split is computed server-side at entry — CGST + SGST for intra-state, IGST for inter-state, never both — HSN is captured at the item, and GSTR-1 is prepared from the vouchers themselves. 2B reconciliation runs against your purchase register supplier by supplier, so an ITC mismatch surfaces while there is still time to make a phone call.