Tax: GST and sales tax

SupplySynk works out the tax on your orders, online checkout and purchase orders from a few settings. Nothing changes until you set it up: a business that hasn't chosen a tax setting charges no tax, exactly as before.

Have your accountant (CA in India) check your settings before you rely on them. SupplySynk works the numbers out the same way every time, but the rules for your business (your registration, your products' rates) are for you and your accountant to decide. Items marked [verify] below are rules we're not certain of yet.

Set it up (owners and admins)

Go to Settings → Tax. Changes apply to new orders only; orders already placed keep the tax they were given.

India

1. How you're registered for GST:
   • Not registered (below the GST limit): no GST is charged or shown.
   • Composition scheme: you pay a small tax on your turnover yourself and can't charge GST to customers, so none is shown on bills.
   • Regular GST: GST is worked out on every sale.
2. GSTIN: needed for composition and regular. We check it (15 characters, your state code, your PAN inside it, and the last check character) and take your state from it.
3. Legal name and trade name, as registered.
4. Prices include GST (on unless you sell from a price list without GST).
5. Usual GST rate: used for products that don't have their own rate.
6. Bill rounding: the total is rounded to the nearest ₹1 with a "Round off" line (you can switch it off).

Locations: if a shop or godown has its own GSTIN (a branch in another state), add it in Settings → Locations. Otherwise each location uses the business GSTIN, and its state comes from its address.

US

1. Collect sales tax: off until you turn it on.
2. Sales tax rate: your combined rate, for example 8.9 (up to 3 decimals). Prices don't include tax; it's added at checkout and on orders.
3. On a product you can choose Exempt (no tax) or a custom rate (say, a reduced food rate). Everything else uses your rate.

One rate per business keeps it simple. Different rates by delivery address aren't supported yet (we only do pickup and in-store sales today).

Products

Products that had a 0% rate: before tax was built, every product had a 0% rate that nothing used. Those now mean "use my usual rate". If some of your products are tax-free, mark them Exempt (US) or give them a 0% GST rate (India) after you turn tax on; SupplySynk reminds you when you do.

Variants follow their family's tax data unless you set it on the variant.

You can fill them in a spreadsheet import with the columns HSN, GST rate, MRP and Unit.

Clothing and footwear take their GST rate from the price of each piece after discount: 5% up to ₹2,500, 18% above (HSN chapters 61 and 62, and footwear headings 6401 to 6405). This happens automatically from the HSN code, whatever rate is on the product. [verify]

How GST is worked out (India, regular)

• Prices include GST, so it's worked out backwards: taxable value = price × 100 ÷ (100 + rate). The customer pays the shelf price.
• Within your state (every sale in your shop, counter and online pickup): half the rate is CGST and half SGST. In Chandigarh, Ladakh, Lakshadweep, Andaman and Nicobar, and Dadra and Nagar Haveli and Daman and Diu it's UTGST instead of SGST.
• To another state (only when an order gives another state as the place of supply; delivery isn't built yet): IGST at the full rate.
• Discounts come off before tax, so they lower the taxable value.
• Each line is worked out to the paisa; CGST and SGST are rounded the same way, so they're always equal and always add up to the line's GST.
• The bill total is rounded to the nearest ₹1 ("Round off").
• Delivery charges aren't taxed yet. Ask your accountant. [verify]

Each order keeps its breakup (taxable value, rate, CGST/SGST/UTGST/IGST per line). You'll see it in the order's details, and GST bills and the GSTR-1 export will be built from it.

Purchase orders (registered businesses): the GST your supplier charges is worked out from each product's rate on its cost (costs don't include GST): CGST + SGST from a supplier in your state, IGST from another state (from the supplier's address). If the supplier has no address, SupplySynk assumes your state and says so on the purchase order. You can type a tax amount instead.

GST bills: invoices and credit notes (India)

For businesses registered for GST (Settings → Tax), SupplySynk issues the bill for each order:

• Tax Invoice (regular GST) or Bill of Supply (composition scheme, with "Composition taxable person, not eligible to collect tax on supplies").
• When: automatically once the whole order is handed over (shipped, or picked up), or any time from the order with Issue GST invoice (for a counter sale before the customer leaves). One per order.
• Numbers run in a series per GSTIN and financial year and start again on 1 April (India time): INV/26-27/000001, INV/26-27/000002…; bills of supply BOS/…, credit notes CN/…. At most 16 characters, never skipped or reused. You can change the invoice prefix (1 to 3 letters or digits, such as BLR; not CN or BOS, which credit notes and bills of supply use) in Settings → Tax; it applies from the next new series.
• A bill never changes once issued. To correct one, issue a credit note. Returns get one automatically for what came back, and cancelling an invoiced order credits it in full. Each credit note refers to its invoice.
• What's printed (Rule 46): your name, address and GSTIN; number and date; the customer (their GSTIN and address for a business customer, and the address of any customer for ₹50,000 or more); HSN, quantity and unit, rate, discount and taxable value; CGST and SGST (or UTGST, or IGST) rate and amount; place of supply; reverse charge (No); total in words; a signature line.
• Business customers (B2B): give the customer's GSTIN, name and billing address on the order, and every item needs an HSN code. A bill of ₹50,000 or more needs any customer's name and address. If something's missing, the bill isn't issued: the order shows GST invoice pending with the reason; fix the order and press Try again (SupplySynk also retries every day). The same goes for a credit note that couldn't be issued.
• Deadline for credit notes: a credit note for a financial year must be issued by 30 November after that year ends (Section 34), so don't leave a pending one waiting.
• Print or share: open the bill from the order, choose A4 or 80 mm (thermal printers), then Print or save as PDF, or Share on WhatsApp (it opens WhatsApp with the bill's summary and its link). The link shows only what's on the bill; anyone with the link can open it.
• Orders whose tax was typed in, came from Square, or were placed before you registered can't get a GST bill.

GST reports (India)

In Settings → Tax, GST reports, pick a month or quarter and download:

• GSTR-1 as JSON for the GST offline tool, or a CSV per table: B2B, B2CL (to another state above ₹1 lakh [verify]), B2CS, credit notes to registered (CDNR) and unregistered (CDNUR) customers, nil-rated, the HSN summary split B2B/B2C, and the documents issued. Built from the bills you issued in the period. Credit notes on small B2C bills reduce the B2CS table.
• Sales register (every bill line; credit notes negative) and purchase register (purchase orders with the GST your suppliers charge; staff and up).
• Tally Prime (managers and up): your bills and credit notes as vouchers, with their ledgers and stock items, to import in Tally. See Tally Prime export.

SupplySynk prepares the data; you or your CA file the return. Check it before filing.

US businesses

US businesses don't get GST bills. The order details show the tax; a printable receipt isn't part of this yet.

Things to check with your CA [verify]

• The ₹2,500 clothing and footwear threshold, which HSN codes it covers, and whether "price per piece" means the price paid or the value without GST (SupplySynk uses the price paid, after discount).
• Delivery charges aren't taxed yet (US or India): should they carry tax (in India, GST at the goods' rate)?
• Your registration limit (₹40 lakh or ₹20 lakh, depending on the state).
• Each product's GST rate and HSN code.
• Older GST rates (before 22 Sep 2025, with 12% and 28%) are kept only for dates before then.
• The B2CL limit (₹1 lakh), and that credit notes on small B2C bills are netted in B2CS rather than listed in CDNUR.
• The GSTR-1 JSON shape against the current offline tool version.
• Issuing the invoice when the order is handed over (Section 31 timing), and the 16-character numbering.

Typing tax yourself (API)

Apps that send their own tax amounts on an order (taxAmount on a line or the order) keep working exactly as before: when any tax amount is given, SupplySynk uses the amounts as given and works nothing out.

For developers

GET/PATCH /api/v1/tax/settings, GET /api/v1/tax/preview (or POST), tax fields on products and orders: see the API guide and the MCP tools get_tax_settings, update_tax_settings and preview_tax. GST bills: POST /api/v1/orders/{id}/invoice, GET /api/v1/gst/documents, POST /api/v1/gst/documents/{id}/credit-note, GET /api/v1/gst/gstr1, GET /api/v1/gst/registers/sales and /purchases, GET /api/v1/gst/tally and /api/v1/gst/tally/settings; MCP issue_gst_invoice, list_gst_documents, create_credit_note.