What does the Build GSTR-1 JSON (Outward Supplies Return) skill do?

Convert a period's sales data into the GSTR-1 offline-utility JSON for the GST portal (gst.gov.in) — sectioned into b2b, b2cl, b2cs, cdnr, exp, hsn, nil and doc_issue, with gstin and fp (MMYYYY), recipient-wise invoices, inter/intra-state tax split (iamt vs camt+samt), B2CL vs B2CS classification, HSN-wise summary, e-invoice auto-population reconciliation, and a worked example filed monthly or quarterly under QRMP

How do I run the Build GSTR-1 JSON (Outward Supplies Return) skill?

Copy the skill and paste it into your own Claude or ChatGPT, then provide your source data. FinchContext skills run inside your own AI assistant, so your financial data never leaves your control.

Which region does the Build GSTR-1 JSON (Outward Supplies Return) skill cover?

India. It targets the local tax authority / e-invoicing format described on this page.

Build GSTR-1 JSON (Outward Supplies Return)

Skill: Convert sales data into the GSTR-1 offline-utility JSON

Region: India Category: Tax — GST returns Does: Takes a period's outward-supply (sales) data and maps it onto the GSTR-1 JSON in the GST offline-utility format — sectioned into b2b, b2cl, b2cs, cdnr, exp, hsn, nil and doc_issue — for upload to the GST portal (or filing via GSP/API). System: GST portal (gst.gov.in) — Returns, GSTR-1 / IFF

GSTR-1 reports outward supplies for a tax period; it is filed monthly (turnover > ₹5 crore or opted-in) or quarterly under QRMP (with the IFF for the first two months of a quarter). The JSON top level carries gstin, fp (filing period MMYYYY) and version/hash. Section structure and code lists change between releases — always generate against the current GSTR-1 offline-tool schema and validate on the portal before filing.

When this applies

A registered taxpayer reporting outward supplies for the period (monthly, or quarterly under QRMP with the optional IFF for invoice upload in months 1–2).
E-invoiced B2B documents auto-populate the b2b section from the IRP — reconcile rather than re-key.
Due 11th of the following month (monthly) / 13th after quarter-end (quarterly).

Input data required

Section	Reports
`b2b`	supplies to registered persons (by recipient GSTIN), invoice-wise with item rate detail
`b2cl`	inter-state B2C invoices to unregistered persons above ₹1,00,000 (invoice-wise, by POS)
`b2cs`	all other B2C (intra-state + small inter-state) — rate-wise summary by POS
`cdnr` / `cdnur`	credit/debit notes to registered / unregistered persons
`exp`	exports (with payment `WPAY` / without payment `WOPAY`), shipping bill detail
`hsn`	HSN/SAC-wise summary of all outward supplies
`nil`	nil-rated, exempt and non-GST supplies
`doc_issue`	document series issued (invoices, credit/debit notes) with from/to and cancelled counts

Document structure (offline-utility JSON)

{
  "gstin": "29AABCU9603R1ZM",
  "fp": "052025",
  "version": "GST3.2.1",
  "hash": "hash",
  "b2b":  [ { "ctin": <recipient GSTIN>,
              "inv": [ { "inum", "idt", "val", "pos", "rchrg", "inv_typ",
                         "itms": [ { "num", "itm_det": { "txval","rt","camt","samt","iamt","csamt" } } ] } ] } ],
  "b2cs": [ { "sply_ty":"INTRA","pos","typ":"OE","txval","rt","camt","samt","csamt" } ],
  "hsn":  { "data": [ { "num","hsn_sc","desc","uqc","qty","txval","rt","iamt","camt","samt","csamt" } ] },
  "doc_issue": { "doc_det": [ { "doc_num":1, "docs":[ { "num":1,"from","to","totnum","cancel","net_issue" } ] } ] }
}

Key rules: rt is the combined GST rate (e.g. 18 even though split into CGST 9 + SGST 9). pos is the 2-digit place-of-supply state code. Intra-state lines carry camt+samt; inter-state carry iamt. inv_typ is R (regular), SEWP/SEWOP (SEZ), DE (deemed export).

Calculation rules

Per item: camt = samt = txval × rt / 2 (intra-state); iamt = txval × rt (inter-state, POS ≠ supplier state).
Invoice val = total invoice value including taxes; sum of itms taxable + tax must reconcile to it.
b2cs is aggregated by POS + rate + supply type (no invoice numbers).
hsn summary must cover all outward supplies and reconcile to the section totals; HSN digit requirement depends on turnover (4/6 digits) and is mandatory rate-wise.

Worked example (one B2B invoice + HSN summary, outline)

{
  "gstin": "29AABCU9603R1ZM",
  "fp": "052025",
  "version": "GST3.2.1",
  "hash": "hash",
  "b2b": [
    {
      "ctin": "29AAACR5055K1Z5",
      "inv": [
        {
          "inum": "INV-2025-0042",
          "idt": "04-05-2025",
          "val": 17700.00,
          "pos": "29",
          "rchrg": "N",
          "inv_typ": "R",
          "itms": [
            { "num": 1, "itm_det": { "txval": 15000.00, "rt": 18.0,
              "camt": 1350.00, "samt": 1350.00, "iamt": 0.00, "csamt": 0.00 } }
          ]
        }
      ]
    }
  ],
  "hsn": {
    "data": [
      { "num": 1, "hsn_sc": "73269099", "desc": "Steel bracket", "uqc": "NOS",
        "qty": 100, "txval": 15000.00, "rt": 18.0,
        "iamt": 0.00, "camt": 1350.00, "samt": 1350.00, "csamt": 0.00 }
    ]
  },
  "doc_issue": {
    "doc_det": [
      { "doc_num": 1, "docs": [ { "num": 1, "from": "INV-2025-0001", "to": "INV-2025-0042",
        "totnum": 42, "cancel": 0, "net_issue": 42 } ] }
    ]
  }
}

Upload via the offline tool or GSP/API; the portal validates and returns a summary for filing.

Validation checklist

Current GSTR-1 offline-tool version / schema used; gstin and fp (MMYYYY) correct
B2B keyed by valid recipient ctin; pos, inv_typ, rchrg set per invoice
Inter-state vs intra-state tax split correct (iamt vs camt+samt) against POS
B2CL (inter-state > ₹1,00,000) vs B2CS (rate-wise summary) classified correctly
exp shipping-bill detail and WPAY/WOPAY flag present for exports
hsn summary covers all supplies and reconciles to section totals (correct HSN digits)
doc_issue series complete; e-invoice auto-populated B2B reconciled, not duplicated
Filed by the due date (11th monthly / 13th quarterly under QRMP)

Last updated: 2026-06-04 — confirm the active schema version, field codes, and portal/API requirements against the current GSTN (gst.gov.in) specifications before use.