CalibreGST verified on every invoice, field by field.
Calibre was designed for the Indian invoice first, not adapted for it later. Every supplier invoice passes four tiers of GST and policy checks before anyone is asked to approve it, and every finding carries the code your reviewers and auditors will see.
Six GST checks, on every invoice.
Built for the Indian invoice from the first line of code: identity, place of supply, rate slabs, arithmetic, amount in words and the signed e-invoice.
- E
GSTIN check digit
Computed from the first fourteen characters and compared with the one printed.
- 36→27
Place of supply
Telangana to Maharashtra is inter-state, so IGST, not CGST and SGST.
- 18%
Rate slab
Every rate must sit on a valid GST slab.
- ±₹1
Arithmetic
Lines, taxes and total agree, to within ₹1 or 0.5%.
- = ₹
Amount in words
“Four Lakh Forty-Seven Thousand…” must equal the figures.
- RS256
Signed QR
The e-invoice QR is verified against the portal’s published keys.
Four tiers of proof before anything clears.
- I · FormGSTIN format and check digit, the PAN inside it and its state code.
GSTIN_STATE_INVALID - I · FormA one-character reading slip in a GSTIN is repaired only to a candidate with a valid check digit, and shown to a reviewer.
GSTIN_REPAIRED - I · FormInvoice numbers within the 16-character limit of GST Rule 46.
INVOICE_NO_FORMAT - I · FormHSN and SAC codes in a valid 4, 6 or 8-digit form.
HSN_FORMAT - II · ArithmeticLine totals and tax splits add up, to within ₹1 or 0.5%.
ARITH_TOLERANCE - II · ArithmeticThe amount in words agrees with the figures, lakhs and crores included.
AMOUNT_WORDS_MISMATCH - III · GST and identityCGST and SGST within a state, IGST across states, checked against the place of supply.
GST_REGIME_UNEXPECTED - III · GST and identityEvery rate sits on a valid GST slab.
GST_RATE_NOT_A_SLAB - III · GST and identitySigned e-invoice QR codes verified against the e-invoice portal’s published keys; verified values are locked.
IRN_SIGNATURE - III · GST and identityReverse-charge invoices recognised, and flagged if the supplier charged tax.
RCM_SUPPLIER_TAX_NONZERO - III · GST and identityYour GSTIN on the invoice matched to the right registration when you have several.
BUYER_GSTIN - IV · PolicyDuplicate invoices caught before approval.
DUPLICATE_INVOICE - IV · PolicyInvoice lines matched to purchase-order lines within the tolerance you set.
PO_LINE_TOLERANCE - PortalIRN status checked with the e-invoice portal.
IRN_STATUS - ReturnsGSTR-2B reconciliation: matched, mismatched and missing invoices.
GSTR2B_MATCH
The signed QR settles it.
An e-invoice carries a QR code signed by the invoice registration portal. Calibre verifies that signature against the portal’s published keys, offline and in milliseconds, then treats the supplier GSTIN, invoice number, date, total and IRN as authoritative. One PDF holding several e-invoices is split at each signature.
GSTR-2B, reconciled.
Calibre reconciles your purchase invoices against GSTR-2B and shows which are matched, which differ and which are missing, so input tax credit is claimed on the right invoices and supplier follow-ups start early.
Check a GSTIN the way Calibre does.
State code, PAN, entity number, the default character and the check digit, with the same one-character repair the product uses.
Runs in your browser; nothing you type is sent anywhere. Specimen GSTINs are fictional. Open the full GSTIN checker.
Calibre reads the amount in words printed on the invoice and compares it with the figures, lakhs and crores included.
GST questions
What GST checks does Calibre run on each invoice?
GSTIN format and check digit, the PAN and state inside it, invoice number length, HSN and SAC format, line and tax arithmetic, amount in words, tax type against the place of supply, rate slabs, reverse charge, your own registration, duplicates and purchase-order matching.
Can Calibre verify e-invoices?
Yes. Calibre verifies the signed QR on an e-invoice against the e-invoice portal’s published keys, then locks the supplier GSTIN, invoice number, date, total and IRN as authoritative values. It can also check an IRN’s status with the portal.
Does Calibre reconcile with GSTR-2B?
Yes. Calibre reconciles your purchase invoices against GSTR-2B and shows which are matched, which differ and which are missing, so input tax credit is claimed on the right invoices.
What happens when a GSTIN is misread?
If one character is misread, Calibre repairs it only to a GSTIN whose check digit is valid, and shows the change to a reviewer. If no single change produces a valid GSTIN, the invoice goes to review with that reason attached.
See it on your own invoices.
Send us a month of invoices. We replay them against your ERP’s records and show you, vendor by vendor, what Calibre would have cleared, and why the rest would have gone to a person.