Interior and fit-out
GST billing software for interior designers and fit-out firms
Send a quotation split by stage, turn the accepted one into an order, and raise a GST invoice for design, carpentry or finishing as each stage is handed over.
In short
SimpleERP is GST billing software for interior designers and fit-out contractors. Quotations are written by stage, accepted ones become sales orders billed in parts, and each invoice carries SAC 998391 or SAC 9954 lines with CGST and SGST or IGST worked out from the site.
Illustration of the keyboard-first invoice editor with a focused line, live tax totals and shortcut hints.
A GST billing day at Nila Interiors
Rekha, who runs the accounts at Nila Interiors in Kochi, starts Monday with three bills to raise. The design fee for a new villa in Kadavanthra is due on sign-off, the carpentry stage at a dental clinic in Edappally finished on Saturday, and a showroom fit-out in Coimbatore needs its civil stage billed before the client's month closes.
Each client reads the bill differently. The villa owner wants the design fee on its own sheet, the clinic wants the modular cabinets and the false ceiling shown as one works line, and the Coimbatore client's accountant checks that the tax is IGST, not CGST and SGST, because the site sits in Tamil Nadu.
In SimpleERP each of these is an invoice raised against a sales order that already holds the agreed stages, so Rekha picks the order, chooses the stage and posts. The client advance taken at sign-off is applied to the first stage invoice from the same screen.
How do I bill a fit-out in stages without retyping the quotation?
Write the quotation with a line for each stage, such as design, civil, carpentry, electrical and finishing, and mark it accepted when the client signs. Convert it to a sales order, and every stage invoice copies the lines it needs from that order.
- The order shows what is billed and what is still open, so nobody bills the carpentry stage twice.
- A changed wardrobe or laminate goes into a revised quotation; the version the client first saw is kept.
- Running bill numbering follows the April to March year, such as INV-2026-27-0048.
Which SAC and HSN codes go on an interior design invoice?
Design and consulting are services, fit-out work done with your own material is usually a works contract, and goods handed over on their own are sold under their HSN code. Set each one up once as an item and the code prints on every line.
Works contract rates depend on the kind of building and the client, so treat these as a starting point. Rates change, so confirm the rate for your goods with your CA or the GST portal before you rely on it.
| What is billed | Code | Example rate |
|---|---|---|
| Interior design fee | SAC 998391 | 18% |
| Design consulting or site advisory | SAC 998399 | 18% |
| Modular kitchen, wardrobe and false ceiling works with material | SAC 9954 | 18% |
| Plywood sold to the client separately | HSN 4412 | 18% |
| Hinges, handles and channels sold separately | HSN 8302 | 18% |
When does a fit-out invoice carry IGST instead of CGST and SGST?
The place of supply comes from the site address on the invoice. The Edappally clinic's carpentry stage of ₹3,20,000 carries CGST ₹28,800 and SGST ₹28,800, while the Coimbatore civil stage of the same value carries IGST ₹57,600, with no setting to change in between.
- One client, many sites, each saved as a ship-to address on the customer.
- GSTIN checked as you type, with the state code read from it.
- The HSN summary at the foot of the invoice and in the sales register for your filer.
Illustration of GST tax invoice INV-2026-27-0213 to Ravi Stores with CGST 9% and SGST 9%, round off, a UPI QR code and the amount in words.
What happens to the client advance taken before work starts?
Record the advance as a receipt against the client. It stays on account until you apply it, usually to the design or civil stage invoice, and the invoice then shows paid or partially paid on its own.
- Part payments by UPI, cheque or bank transfer reduce the stage balance as they arrive.
- A UPI QR on the printed invoice for clients who pay from their phone.
- The customer statement lists every stage, receipt and balance for the final settlement.
One system
What it connects to
A stage invoice writes the receivable and the output GST, and any plywood or hardware line issues stock from the site it sits in.
Interior and fit-out
Staged quotations, SAC-coded design and works bills, plywood and hardware per site, and payroll for carpenters and supervisors.
See howInventory for interior contractors
Plywood, laminate and hardware stock in the store and at each site, leftovers moved between sites and reorder levels on fast movers.
See howAccounting for interior design firms
Stage receivables, subcontractor payables, client advances and GST in one ledger, with month-end checks a studio can actually run.
See howGST billing
Tax invoices with CGST, SGST or IGST by place of supply, HSN on every line and a UPI QR on the print.
See howQuotation format
A quotation format with GST shown line by line, as a free Excel, Word and PDF download.
See how
Honest limits
Not included yet
- E-invoice IRN and QR code, and e-way bills, are not generated through the government APIs
- Cess is not calculated; GST return filing stays with you or your accountant
- No price lists: every line is priced as you bill it
- No RA-bill or measurement sheet format: each running bill is a normal tax invoice against the sales order
- Amounts a client holds back as retention are not tracked separately; they stay open on the stage invoice
Getting started
Start with GST billing
Sign up with your phone
Name, phone number and a password. No card for the seven-day trial, and email is optional.
Tell us about the business
Type your GSTIN and the state fills itself. Accounts, GST rates, units, roles and numbering are seeded for you.
Add what you sell
Add the design fee and each kind of works as a service with its SAC code, and plywood, laminate and hardware you sell on their own as products with an HSN code.
Post your first GST invoice
Pick the customer, add lines and save. The place of supply picks CGST and SGST or IGST for you.
FAQ
Questions, answered
Can I put the design fee and the carpentry works on one invoice?
Yes. Each line keeps its own SAC code and rate, so a design line and a works line can share a bill. Many studios still bill design separately because the fee falls due long before the works start.
Can a quotation show the stage totals the client asked for?
Write each stage as its own line, or as a group of lines with a clear description, and the printed quotation shows each with its amount and tax. There is no separate BOQ import; lines are typed or picked from your items.
The client deducted TDS from our stage payment. How do I record it?
Record the money that actually reached the bank as the receipt. There is no screen for TDS deducted by clients yet, so your accountant posts that part with a manual journal.
Does SimpleERP generate e-invoices for large fit-out clients?
No. It does not connect to the e-invoice portal or create an IRN. If your turnover puts you under e-invoicing, the invoice data still has to go through the government portal or your filer's tool.
Related
Keep reading
Interior and fit-out
Staged quotations, SAC-coded design and works bills, plywood and hardware per site, and payroll for carpenters and supervisors.
Read moreInventory for interior contractors
Plywood, laminate and hardware stock in the store and at each site, leftovers moved between sites and reorder levels on fast movers.
Read moreAccounting for interior design firms
Stage receivables, subcontractor payables, client advances and GST in one ledger, with month-end checks a studio can actually run.
Read more
See how GST billing works in SimpleERP for interior and fit-out
Seven days free. No card. Your first GST invoice in minutes.