GSTR-1, GSTR-1A, IMS, GSTR-2B and GSTR-3B: Monthly GST Flow
The modern GST return process involves supplier reporting, recipient actions, ITC statements and liability filing. This guide connects the monthly flow.
GST compliance is easier to understand when the forms are viewed as one connected monthly process instead of separate tasks.
The practical flow is broadly:
Books → GSTR-1 → GSTR-1A if required → recipient IMS actions → GSTR-2B → GSTR-3B → books reconciliation.
Step 1: GSTR-1 — supplier reports outward supplies
The supplier reports outward-supply details through GSTR-1 or the applicable quarterly mechanism.
The sales register, e-invoice data, debit notes and credit notes should be reconciled before filing so that corrections do not become the normal process.
Step 2: GSTR-1A — same-period correction window
If the supplier discovers an eligible omission or error after GSTR-1, GSTR-1A provides an optional same-period amendment opportunity before GSTR-3B is filed.
It can be filed only once for the period, so a controlled review is important.
Step 3: IMS — recipient reviews supplier records
Eligible supplier records flow into the recipient's Invoice Management System.
The recipient can review the records and, depending on the document, use actions such as Accept, Reject or Pending.
The purchase register should be the internal reference for deciding whether the invoice belongs to the business and whether supplier follow-up is needed.
Step 4: GSTR-2B — ITC statement
GSTR-2B is the auto-drafted ITC statement used as an important input for GSTR-3B.
It is not enough to claim everything appearing in GSTR-2B. The taxpayer must separately evaluate legal eligibility, blocked credits, temporary reversals and other conditions.
Step 5: GSTR-3B — liability and ITC reporting
GSTR-3B is where outward tax liability, eligible ITC and other prescribed amounts are finally reported and tax is discharged for the period.
The numbers should reconcile with both the sales side and purchase/ITC side of the books.
A practical monthly reconciliation
- Sales register vs GSTR-1/GSTR-1A;
- Purchase register vs IMS;
- Purchase register vs GSTR-2B;
- Eligible ITC working vs GSTR-3B;
- Output tax ledger vs GSTR-3B liability; and
- GST payable/receivable ledgers vs electronic ledgers.
Why this matters for accountants
When these reconciliations are postponed until year-end, the team often faces hundreds of unmatched invoices and unexplained GST balances.
A monthly process creates cleaner books and makes financial statement preparation much easier.
assureOffice Financial Builder can then use reviewed Tally or Excel balances to prepare structured financial statements without requiring the team to rebuild the accounting presentation manually.
The best GST workflow is not form-by-form. It is one continuous reconciliation from books to returns and back to books.