What does the Build GSTR-3B JSON (Summary Return) skill do?

Convert summary GST figures into the GSTR-3B offline-utility JSON for the GST portal — Table 3.1 outward and inward reverse-charge supplies, Table 3.2 inter-state to unregistered/composition/UIN, Table 4 eligible ITC reconciled to GSTR-2B, Table 5 exempt/non-GST inward, and Table 6.1 tax payment with IGST-first set-off, net cash per head, interest and late fee, and a worked example filed monthly or quarterly under QRMP

How do I run the Build GSTR-3B JSON (Summary 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-3B JSON (Summary Return) skill cover?

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

Build GSTR-3B JSON (Summary Return)

Skill: Convert summary GST figures into the GSTR-3B JSON

Region: India Category: Tax — GST returns Does: Takes a period's summary GST figures and maps them onto the GSTR-3B JSON in the GST offline-utility format — Table 3.1 (outward + inward reverse-charge supplies), Table 3.2 (inter-state to unregistered/composition/UIN), Table 4 (eligible ITC), Table 5 (exempt/nil/non-GST inward), and Table 6.1 (tax payment) — for upload to the GST portal (or filing via GSP/API). System: GST portal (gst.gov.in) — Returns, GSTR-3B

GSTR-3B is the self-assessed summary return reconciling output tax and input tax credit (ITC) and discharging the net liability. It is filed monthly (turnover > ₹5 crore or opted-in) or quarterly under QRMP. From recent changes the liability (Table 3) is auto-drafted from GSTR-1/IFF and the ITC (Table 4) from the auto-generated GSTR-2B — reconcile rather than re-key. The JSON top level carries gstin, ret_period (MMYYYY). Table structure and code lists change between releases — generate against the current GSTR-3B offline-tool schema and validate on the portal before filing.

When this applies

A registered regular taxpayer discharging GST liability for the period (monthly, or quarterly under QRMP).
Due 20th of the following month (monthly); 22nd/24th after quarter-end (QRMP, staggered by state).
Tax is paid by debiting the electronic cash and credit ledgers; the return cannot be filed until the liability in Table 6.1 is fully discharged.

Input data required

Table	Reports
`sup_details` (3.1)	(a) outward taxable (other than zero/nil/exempt), (b) zero-rated, (c) nil/exempt, (d) inward reverse charge, (e) non-GST outward — taxable value + IGST/CGST/SGST/Cess
`inter_sup` (3.2)	of 3.1, inter-state supplies to unregistered, composition, and UIN holders, by POS
`itc_elg` (4)	ITC available (import, reverse charge, ISD, all-other), ITC reversed, net ITC, ineligible
`inward_sup` (5)	composition/exempt/nil-rated and non-GST inward supplies (inter/intra split)
`tx_pmt` (6.1)	tax payable per head, paid through ITC vs cash, interest and late fee

Document structure (offline-utility JSON)

{
  "gstin": "29AABCU9603R1ZM",
  "ret_period": "052025",
  "sup_details": {
    "osup_det":    { "txval","iamt","camt","samt","csamt" },   // 3.1(a) outward taxable
    "osup_zero":   { "txval","iamt","csamt" },                 // 3.1(b) zero-rated
    "osup_nil_exmp":{ "txval" },                               // 3.1(c) nil/exempt
    "isup_rev":    { "txval","iamt","camt","samt","csamt" },   // 3.1(d) inward reverse charge
    "osup_nongst": { "txval" }                                 // 3.1(e) non-GST
  },
  "inter_sup": { "unreg_details":[ {"pos","txval","iamt"} ], "comp_details":[...], "uin_details":[...] },
  "itc_elg": {
    "itc_avl":[ {"ty":"IMPG"|"IMPS"|"ISRC"|"ISD"|"OTH","iamt","camt","samt","csamt"} ],
    "itc_rev":[ {"ty":"RUL"|"OTH","iamt","camt","samt","csamt"} ],
    "itc_net":{ "iamt","camt","samt","csamt" },
    "itc_inelg":[ {"ty":"RUL"|"OTH","iamt","camt","samt","csamt"} ]
  },
  "inward_sup": { "isup_details":[ {"ty":"GST"|"NONGST","inter","intra"} ] },
  "tx_pmt": { "txpd":[ {"sgst":{...},"cgst":{...},"igst":{...},"cess":{...}} ] }
}

Key rules: iamt=IGST, camt=CGST, samt=SGST, csamt=Cess. Inter-state outward carries IGST; intra-state carries CGST+SGST. ITC type IMPG=import of goods, IMPS=import of services, ISRC=inward reverse charge, ISD=Input Service Distributor, OTH=all other ITC.

Calculation rules

Output tax (Table 3.1) is the sum of period output IGST/CGST/SGST/Cess.
Net ITC = ITC available (4A) − ITC reversed (4B); cross-utilisation order is IGST credit first against IGST, then CGST/SGST, per the set-off rules.
Net cash payable per head = output liability − ITC set off for that head; the shortfall is paid from the cash ledger.
Interest at the notified rate applies to delayed/short payment; late fee applies for late filing.
Table 3.2 figures are a subset of Table 3.1 (inter-state to unregistered/composition/UIN) and must not exceed them.

Worked example (monthly, outline)

{
  "gstin": "29AABCU9603R1ZM",
  "ret_period": "052025",
  "sup_details": {
    "osup_det":  { "txval": 1500000.00, "iamt": 90000.00, "camt": 90000.00, "samt": 90000.00, "csamt": 0.00 },
    "osup_zero": { "txval": 0.00, "iamt": 0.00, "csamt": 0.00 },
    "osup_nil_exmp": { "txval": 0.00 },
    "isup_rev":  { "txval": 50000.00, "iamt": 9000.00, "camt": 0.00, "samt": 0.00, "csamt": 0.00 },
    "osup_nongst": { "txval": 0.00 }
  },
  "inter_sup": {
    "unreg_details": [ { "pos": "27", "txval": 200000.00, "iamt": 36000.00 } ]
  },
  "itc_elg": {
    "itc_avl": [
      { "ty": "ISRC", "iamt": 9000.00, "camt": 0.00, "samt": 0.00, "csamt": 0.00 },
      { "ty": "OTH",  "iamt": 30000.00, "camt": 60000.00, "samt": 60000.00, "csamt": 0.00 }
    ],
    "itc_rev": [ { "ty": "OTH", "iamt": 0.00, "camt": 0.00, "samt": 0.00, "csamt": 0.00 } ],
    "itc_net": { "iamt": 39000.00, "camt": 60000.00, "samt": 60000.00, "csamt": 0.00 },
    "itc_inelg": [ { "ty": "OTH", "iamt": 0.00, "camt": 0.00, "samt": 0.00, "csamt": 0.00 } ]
  },
  "tx_pmt": {
    "txpd": [ {
      "igst": { "tx": 99000.00, "citc": 39000.00, "cgst_itc": 0.00, "sgst_itc": 0.00, "csamt_itc": 0.00, "csh": 60000.00, "intr": 0.00, "fee": 0.00 },
      "cgst": { "tx": 90000.00, "citc": 60000.00, "csh": 30000.00, "intr": 0.00, "fee": 0.00 },
      "sgst": { "tx": 90000.00, "citc": 60000.00, "csh": 30000.00, "intr": 0.00, "fee": 0.00 },
      "cess": { "tx": 0.00, "citc": 0.00, "csh": 0.00, "intr": 0.00, "fee": 0.00 }
    } ]
  }
}

Upload via the offline tool or GSP/API; the portal validates, offsets the liability against the ledgers, and enables filing once paid.

Validation checklist

Current GSTR-3B offline-tool version / schema used; gstin and ret_period (MMYYYY) correct
Table 3.1 outward heads complete; inter-state vs intra-state tax split correct (IGST vs CGST+SGST)
Inward reverse charge 3.1(d) reported (and the matching ITC claimed under ISRC)
Table 3.2 inter-state to unregistered/composition/UIN is a subset of 3.1 and does not exceed it
Table 4 ITC reconciled to GSTR-2B; reversals (Rule 42/43, etc.) in 4B; ineligible separated
Set-off order correct (IGST credit first); net cash per head computed in Table 6.1
Liability fully discharged (cash + credit) before filing; interest/late fee added if late
Filed by the due date (20th monthly / 22nd–24th QRMP); reconciles with GSTR-1

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.