The problem: invoicing disconnected from the work
For many Indian manufacturers and contractors, the invoice is the last step of a long process — and the only one done in accounting software. Everything before it lives elsewhere. That gap causes predictable trouble:
- Quantities and rates are retyped, so invoices disagree with the delivery or the certified bill.
- CGST and SGST are charged where IGST was due, or the other way round.
- Invoice numbers are reused or skipped when two people raise bills in parallel.
- HSN codes are missing or inconsistent across invoices for the same product.
- At month end, someone reconciles sales data by hand before GSTR-1 can be prepared.
Raising the invoice inside the ERP, from the record of what was actually supplied, removes most of this.
How GST invoicing works in India
A few rules shape every tax invoice. This is general information; check specifics with your tax advisor.
- Tax split by place of supply. Where the supplier and the place of supply are in the same state, CGST and SGST apply; otherwise IGST. For goods, place of supply generally follows where the goods are delivered. For services related to immovable property — most construction work — it is the location of the property.
- Rates. GST is charged at the applicable rate for the goods or services, which depends on their classification. Rates are not fixed for an industry, so confirm them for your items.
- HSN and SAC codes. Goods are classified by HSN code and services by SAC. Businesses above the turnover threshold must show more digits on B2B invoices.
- Numbering. Invoice numbers must be consecutive and unique within a financial year.
- Deductions at source. Customers may deduct income-tax TDS, and certain government bodies deduct GST TDS. Both need to be recorded against the invoice so receivables are right.
- Returns. Outward supplies are reported in GSTR-1 — by the 11th of the following month for monthly filers — and tax is paid through GSTR-3B, due by the 20th for monthly filers. Quarterly filers under the QRMP scheme follow different dates.
- E-invoicing. Businesses above the notified turnover threshold must register B2B invoices on the Invoice Registration Portal to obtain an IRN.
What to look for in a GST invoicing ERP
- Invoices created from the source document, not retyped.
- Automatic CGST/SGST/IGST from place of supply.
- HSN/SAC on every line.
- Gap-free numbering per financial year, safe with several users.
- Tax fixed at creation, so later master-data changes do not alter issued invoices.
- TDS recording and a clear receivables position.
- Return preparation and checks before your advisor files.
- Online payment that reconciles itself.
A month-end check worth running
Before choosing any system, look at last month’s sales register and ask how long it took to answer three questions: do the invoice numbers run without gaps, does every B2B invoice carry the customer’s correct GSTIN and place of supply, and does the total output tax agree with what was paid in GSTR-3B? If any of these needed a manual reconciliation, that is the work a GST invoicing ERP should remove. The answer should come from the invoices themselves, not from a spreadsheet maintained alongside them.
How Zaptiz handles GST invoicing
Zaptiz Electrical
In Zaptiz Electrical, invoices are raised from the sales order or straight from a delivery note, so what is billed matches what was dispatched.
- CGST, SGST or IGST with HSN on each line.
- GST is calculated once, when the invoice is created, and stored with it.
- Gap-free numbering per financial year, plus proforma invoices.
- TDS or TCS on sales invoices, with a TDS/TCS register and CSV export.
- Pay-Now links and QR through your own Razorpay or Stripe, reconciled automatically.
- Receipts, ageing and emailed payment receipts; P&L, balance sheet, cash flow and trial balance.
- The GST agent computes GSTR-1 and GSTR-3B figures, runs about 20 checks, gives a health score and keeps a filing calendar. It never files.
Zaptiz Construction
In Zaptiz Construction, the tax invoice is created from a certified RA bill, so the invoice follows the client’s certification rather than your claim.
- Place of supply is the site, which sets CGST and SGST or IGST.
- TDS fields are included, for income-tax TDS and GST TDS where the client deducts it.
- Invoices are sent by email or WhatsApp, with a pay link through your own Razorpay or Stripe.
- Payments are recorded in a company-wide register and allocated against invoices.
- The GST & TDS agent runs monthly output GST and TDS checks with a filing calendar.
Common to both
Customers, vendors, invoices and purchase orders can be pushed to Zoho Books. Neither product generates e-invoices (IRN) or e-way bills yet, neither has a Tally connector, and neither files returns. Zaptiz Construction does not issue credit notes. See Integrations for current status.
For more on how retention and advances interact with billing, read RA bills, retention and advances.
Get started
Panel manufacturers can test invoicing end to end in the 9-day free trial of Zaptiz Electrical. Contractors can book a demo of Zaptiz Construction with their own certified bill. Plans are on the pricing page.