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Gstr1 Review

  • 1 installs
  • 2 repo stars
  • Updated May 14, 2026
  • eurth/claude-for-ca

Reviews GSTR-1 outward-supply data before filing, checking B2B/B2C/export classification, HSN summary, e-invoice linkage, and sales-register mismatches.

About

Validates Indian GST GSTR-1 return data before submission across supply classification, HSN codes, place of supply, and reconciliation with the sales register, for monthly and QRMP/IFF filers. A chartered accountant uses it to review outward supplies before filing, without submitting.

  • Classifies supplies into the correct GSTR-1 tables (B2B, B2C, exports)
  • Reviews only; filing requires partner-verified HITL approval

Gstr1 Review by the numbers

  • 1 all-time installs (skills.sh)
  • Ranked #909 of 1,106 Finance & Trading skills by installs in the Skillselion catalog
  • Data as of Jul 8, 2026 (Skillselion catalog sync)
npx skills add https://github.com/eurth/claude-for-ca --skill gstr1-review

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Listed on Skillselion
Installs1
repo stars2
Last updatedMay 14, 2026
Repositoryeurth/claude-for-ca

What it does

Reviews GSTR-1 outward-supply data before filing, checking B2B/B2C/export classification, HSN summary, e-invoice linkage, and sales-register mismatches.

Files

SKILL.mdMarkdownGitHub ↗

GSTR-1 Review

FINANCIAL INTEGRITY: GSTR-1 review only. Do NOT file or submit until the partner has verified all items and triggered the GST Filing HITL approval step.

Firm Context

!python3 ${CLAUDE_PLUGIN_ROOT}/../../shared/bin/get-firm-context.py 2>/dev/null || echo "Run /cold-start:onboard-firm to set up firm profile"

Step 1 — Client and Period

Ask (if not provided):

  • Client name / GSTIN
  • Return period (Month-Year for monthly, Quarter for QRMP)
  • Are they a QRMP filer? (IFF for first two months, quarterly GSTR-1 for Q3)

Step 2 — Collect Source Data

Accept data in any format:

  • Excel/CSV export from Tally or billing software
  • Pasted table
  • JSON from pdf-data-extractor skill

Or pull directly from GST portal:

  • mcp__gst_portal__get_gstr1_draft(gstin, period) — fetches saved draft from portal

Step 3 — Classification Review

For each supply, verify the correct table:

Supply TypeGSTR-1 TableCriteria
B2B TaxableTable 4Registered buyer, GSTIN provided
B2C LargeTable 5Unregistered, invoice value > Rs.2.5L inter-state
B2C SmallTable 7Unregistered, invoice value ≤ Rs.2.5L
Zero-Rated ExportsTable 6A/6BExport with/without LUT
Nil / Exempt / Non-GSTTable 8No tax charged
Reverse ChargeTable 4BServices from unregistered dealers
Advances ReceivedTable 11AAdvance received, supply not made
Debit/Credit NotesTables 9/10CDN for B2B/B2C

Flag if:

  • Registered buyer invoice placed in B2C table (revenue leakage risk for buyer)
  • GSTIN in Table 4 does not pass format validation (15 chars, state code, PAN-embedded)
  • Place of supply does not match buyer's state (CGST+SGST vs IGST mismatch)

Step 4 — HSN Summary Validation (Table 12)

For turnover > Rs.5 Cr: 6-digit or 8-digit HSN mandatory For turnover Rs.1.5–5 Cr: 4-digit HSN mandatory For turnover < Rs.1.5 Cr: HSN optional but recommended

Check:

  • [ ] All HSN codes are valid (cross-check against HSN master)
  • [ ] HSN-level taxable value and tax amounts match sum of invoice details
  • [ ] Unit of Measurement (UOM) is valid GST-approved UOM
  • [ ] 8-digit HSN for pharma/chemicals/textiles (as notified)

Step 5 — E-Invoice Reconciliation (for turnover > Rs.10 Cr)

If client is e-Invoice mandated (turnover > Rs.10 Cr w.e.f. 1 Apr 2023):

  • [ ] Every B2B invoice above Rs.0 must have an IRN (Invoice Reference Number)
  • [ ] IRN is 64-character hash
  • [ ] E-way bill auto-generated for consignment value > Rs.50,000
  • [ ] Cancel-and-reissue invoices have separate IRN with cancellation reason

Flag: Any B2B invoice without IRN for e-Invoice mandated taxpayer = portal rejection

Step 6 — Summary Comparison

Pull GSTR-1 summary and compare with:

  • Sales Register total (from Tally or accounting software)
  • E-Invoice data (if applicable)
  • Previous month's GSTR-1 (for unusual jumps)

Present comparison table:

GSTR-1 Review Summary — [Client Name] | GSTIN: [GSTIN] | Period: [Period]
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
SOURCE                 | TAXABLE VALUE   | CGST     | SGST     | IGST     | TOTAL
GSTR-1 Draft           | Rs.XX,XX,XXX    | Rs.X,XXX | Rs.X,XXX | Rs.X,XXX | Rs.XX,XXX
Sales Register (Tally) | Rs.XX,XX,XXX    | Rs.X,XXX | Rs.X,XXX | Rs.X,XXX | Rs.XX,XXX
Difference             | Rs.XX,XXX ⚠     | Rs.XX    | Rs.XX    | Rs.XX    | Rs.XX,XXX

Step 7 — Exceptions List

Present all exceptions for CA review:

EXCEPTIONS REQUIRING YOUR REVIEW:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1. ⚠ Invoice Nos. 45, 67: Registered buyer (GSTIN present) filed in B2C table
   → Move to B2B (Table 4) or confirm buyer is unregistered
2. ⚠ Invoice No. 89: IGST charged, both parties in AP (should be CGST+SGST)
   → Verify place of supply
3. ⚠ GSTR-1 taxable value Rs.2,34,000 > Sales Register Rs.2,31,500
   → 3 invoices appear in portal not in Tally — check for manual invoices
4. ⚠ HSN 85176990: Total value Rs.5,80,000 but tax @ 18% = Rs.1,04,400, portal shows Rs.1,02,000
   → Recalculate or check for non-taxable invoices in this HSN
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Total: 4 exceptions | After resolving, proceed to GSTR-3B review

Step 8 — Due Date Reminder

  • Monthly filer (normal): 11th of next month
  • QRMP (IFF for Months 1 and 2): 13th of next month
  • QRMP (Quarterly GSTR-1): 13th of first month after quarter
  • Late filing: Rs.50/day (Rs.25 CGST + Rs.25 SGST) | NIL filer: Rs.20/day
DUE DATE REMINDER:
GSTR-1 for [Period]: Due [Date]
Days remaining: [N] days
Late fee (if filed on date): Rs.[X]

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