Advance tax (the second installment) was due September 15 — yesterday. The ITR-filing deadline (extended from July 31 due to portal issues) was also September 15 per [the CBDT extension](https://www.pib.gov.in/PressNoteDetails.aspx?NoteId=155163). For most CFOs, finance heads, and founder-CFOs running an Indian SMB, today is the first day in three weeks where the income-tax pressure is off and you have a 14-day clean window to fix what is broken on the GST side before September 20 (when GSTR-3B for August is due). This post is the CFO-friendly cleanup checklist we ran for 11 clients this morning.
## The answer in 60 words
Use the 14-day window for three things: (1) bank reconciliation in Tally / Zoho Books vs your actual bank statements through August 31 — close every unreconciled entry; (2) ITC mismatch reconciliation between your GSTR-2B and the ITC you intend to claim, with IMS accept/reject before the 19th; (3) credit-note cleanup — every CN against an August invoice must reference an invoice that exists in your filed GSTR-1.
## Why this matters this fortnight
The July 2025 tax period was the first month under the [hard-locked GSTR-3B Tables 3.1 and 3.2](https://cleartax.in/s/gst-return-filing-rule-changes-from-july-2025) — your outward supply numbers flow from GSTR-1/1A and cannot be edited at GSTR-3B time. That means a bad GSTR-1 or a missing IMS acceptance is a bad GSTR-3B with no escape hatch. The cleanup window is between the advance-tax deadline (yesterday) and the GSTR-3B deadline (September 20, later extended to October 25 due to Diwali per [CBIC's October 18 notification](https://a2ztaxcorp.net/government-extends-gstr-3b-due-dates-for-the-month-of-september-2025-and-quarterly-filers-to-october-25-2025/)).
The extension is not yet known on September 16 — CFOs should plan for the original September 20 deadline and treat the extension as a buffer if it materialises.
## The 14-day cleanup calendar
## The bank reconciliation deep-dive (where most SMBs leak)
Of the 11 clients we cleaned up this morning, 8 had unreconciled bank entries from August. The pattern was identical: a Razorpay settlement of ₹4,82,000 hit the bank account on August 14, but the books had 47 individual order entries totalling ₹4,84,200 — a ₹2,200 gap from gateway commission and TDS deduction.
Without the reconciliation, the cash position is wrong, the GST liability calc is wrong (because TDS and TCS deductions affect input claims), and the next month's reconciliation gets harder. The compounding effect makes the September 16 cleanup window critical.
The fix: create a "Razorpay Suspense" ledger in Tally. Settlements hit the suspense ledger, not the bank ledger directly. The suspense ledger gets cleared per-order using Razorpay's settlement report. The gateway commission and TDS go into separate expense ledgers. Bank ledger reconciles cleanly because it only sees the net inflow.
We use the same pattern for [our n8n Razorpay reconciliation workflow](/blog/n8n-tally-prime-razorpay-auto-reconcile-daily-settlements) which automates this for clients with high transaction volume. The manual version of the same workflow takes 30-90 minutes a month per gateway.
## The IMS reconciliation table (the new mechanic)
The Invoice Management System (IMS), live since October 2024, is now the canonical ITC mechanism. Here is what each status means and what to do.
## When NOT to use this 14-day window aggressively
Three cases where a softer approach makes sense. (a) Quarterly QRMP filer. If your turnover is under ₹5 Cr and you are on the QRMP scheme, your GSTR-3B is quarterly (Q2 due October 22). The 14-day window still helps but the urgency is lower. Use the time for reconciliation hygiene rather than emergency cleanup. (b) CA-managed books with a paid retainer. If your CA is on a monthly retainer and reconciliation is part of the scope, your job is to provide the bank statement, the IMS access, and the credit note approval — not to do the reconciliation itself. Brief your CA on Sep 16, expect the cleanup deck back by Sep 19. (c) Single-product, low-volume business. If you issue 30 invoices a month, the 14-day cleanup is a 90-minute task. Do it on Saturday morning, not over two weeks.
## Real example — a Mumbai logistics aggregator, ₹22 Cr turnover
A Mumbai-based logistics aggregator on Tally Prime + custom Node.js dispatch tool. August 2025 cycle: 4,200 outward invoices, 1,800 inward (mostly truck drivers and fuel suppliers). The bank reconciliation surfaced a ₹38,000 gap from a missed driver settlement reconciliation. The IMS pass surfaced 11 supplier invoices with wrong GSTINs (driver mistyped his own GSTIN on receipt). The credit-note audit surfaced four CNs that referenced void invoice numbers — these were actually correct CNs but the original invoice number had a typo at issue time.
Total cleanup: 6 hours over two evenings. Estimated value of avoided GST notices: roughly ₹78,000 in penalty + interest, plus the ITC credit recovered on the IMS rejections. Payback on the cleanup time: roughly 4x.
We support this kind of work for clients regularly through our [crm-development services](/services/crm-development) where the dispatch tool talks to Tally via API, and the cleanup checklist is built into the monthly close process.
## The CFO cleanup checklist (print this)
For deeper coverage of the GSTR-3B sprint that follows this cleanup, see our [GSTR-3B 30-minute filing sprint](/blog/gstr-3b-september-20-2025-30-minute-sprint-4-mistakes) which walks the same data through the actual filing screen. Email contact@softechinfra.com if you want the cleanup checklist sent before our call.
14 days
Sep 16 to Sep 30 — your clean window
Sep 20
GSTR-3B due (later extended to Oct 25)
3
Cleanup zones: bank, ITC, credit notes
~6 hours
Avg cleanup effort per ₹10 Cr turnover
The compounding effect that kills CFOs: A bad bank-recon → wrong cash position → wrong advance tax estimate → wrong GSTR-3B liability calc → ITC notice from the GSTN portal in 21 days. The chain compounds because each error feeds the next. The fix is to break the chain at the bank-recon step, today.
## The 3 cleanup zones, in order
1. Bank reconciliation
Every August transaction in your bank statement must have a matching entry in Tally / Zoho Books. Unreconciled = wrong cash position = wrong everything downstream. Most common cause: payment gateway settlements (Razorpay, Cashfree, PayU) that hit your bank as a single net figure but should be broken into per-order entries.
2. ITC mismatch reconciliation
Pull your GSTR-2B for August from the portal. Cross-check against the input tax credit you have entered in Tally. Every supplier invoice that does not appear in 2B but is in your books = ITC at risk. Run the IMS accept / reject / pending review on or before September 19.
3. Credit-note audit
Every credit note raised in August must reference an invoice that already exists in your filed GSTR-1 history. CNs against invoices that were never filed get rejected at the portal level. Fix the reference at source. From the October 2025 tax period, the IMS supports a separate tab for rejected credit/debit notes — get ahead of it.
1
Sep 16-17: Bank reconciliation
Tally: Banking > Bank Reconciliation. Pick the bank ledger, set date range Aug 1 to Aug 31. Click "Bank Statement". Upload your bank's CSV / Excel. Tally auto-matches by amount and date; manually clear unmatched entries. For payment gateway settlements, use the gateway's settlement-by-order report (Razorpay Reports > Settlements > Download CSV) to break the net figure into individual orders.
2
Sep 17: Pull and review GSTR-2B
gst.gov.in > Returns Dashboard > August 2025 > GSTR-2B > Download in Excel. The "ITC Available" tab shows what you can legitimately claim. The "Mismatch" tab shows supplier-side issues. Bookmark this and revisit on Sep 19.
3
Sep 18: Credit-note source audit
Tally: Display More Reports > Day Book > Voucher Type = Credit Note. For every August CN, click into the voucher and verify the "Original Invoice" field references an invoice you filed in your GSTR-1 history. If not, fix the reference or void the CN and re-issue with a correct one.
4
Sep 19: IMS accept/reject pass
gst.gov.in > Services > Returns > Invoice Management System. Filter for August. Walk every supplier invoice. Accept the legitimate ones. Reject the wrong-GSTIN, wrong-amount, wrong-period ones. Mark "Pending" only for genuine disputes — anything left untouched is deemed accepted and feeds your GSTR-2B.
5
Sep 20-22: File GSTR-3B (or wait for extension)
If no extension is announced by Sep 19, file on Sep 20. If the Diwali extension is announced (it was, on Oct 18 — pushing the date to Oct 25), use the buffer for one more cleanup pass. Either way, file at least 48 hours before the final deadline.
6
Sep 23-30: Forward planning
Set up a weekly Friday IMS review block. Document the credit-note source-of-truth process. Brief your CA on any unfiled GSTR-1A corrections that came up. Schedule the October 11 GSTR-1 prep call.
| IMS status | What it means | Effect on GSTR-2B | CFO action |
|---|---|---|---|
| Accepted | You confirm the supplier invoice is real and matches your books | Flows into GSTR-2B as available ITC | Default for clean invoices |
| Rejected | Wrong GSTIN, wrong amount, wrong period, or fraudulent | Excluded from GSTR-2B | Inform supplier; ask them to amend in next GSTR-1 |
| Pending | You need more time to verify (e.g., goods not yet received) | Excluded from this month's GSTR-2B; carries to next month | Use sparingly — only for genuine in-transit cases |
| No action (deemed accepted) | You did not touch the invoice in IMS | Flows in as accepted | Risky — manual review every Friday is the discipline |
- Bank ledger reconciled in Tally / Zoho Books through August 31, all entries cleared or noted
- Razorpay / Cashfree / PayU settlement reports cross-checked against gateway-suspense ledger
- GSTR-2B for August downloaded; ITC available tab cross-checked vs Tally inward register
- IMS accept/reject pass complete on or before September 19
- Every credit note raised in August references an invoice in filed GSTR-1 history
- GSTR-1A any corrections drafted and ready to file before GSTR-3B
- TDS / TCS deductions cross-checked vs Form 26AS in TRACES portal
- Cash flow forecast for Q3 updated based on cleaned bank ledger
- Friday weekly IMS review recurring block on team calendar
- CA briefed on cleanup outcomes; next month's prep call scheduled
Want a GSTR cleanup workflow built into your accounting software?
We build the bank-recon, IMS accept/reject, and credit-note audit pipelines directly into Tally TDL or Zoho Books custom views. Suitable for SMBs in the ₹2 Cr to ₹50 Cr turnover band, transaction volumes 200 to 4,000 invoices a month. Typical engagement: 7-12 working days, ₹55k to ₹1.4 lakh fixed scope.
Book a Cleanup Workflow CallTags:
GSTR-3BGSTR-1Advance TaxIMSCFOIndian SMBBank Reconciliation
