Quick answer: A GST-compliant garage invoice needs six things: a unique sequential invoice number, your GSTIN and the customer's details, each service and part listed with its HSN or SAC code, the correct CGST/SGST or IGST split shown separately, the grand total in figures and words, and an authorised signature.
Key takeaways
- Use one unbroken invoice number series per financial year — gaps and duplicates are the most common audit flag.
- Record the customer name, address, phone and GSTIN (if they have one), plus the vehicle registration number and odometer reading.
- Every line item needs its HSN (parts) or SAC (labour) code — this is not optional on a GST invoice.
- Show CGST and SGST as separate lines for in-state customers; show a single IGST line for out-of-state customers.
- Display the total in words as well as figures, and state your payment terms on the invoice itself.
A clean, GST-compliant invoice is the foundation of a professional garage. It keeps your tax filings clean, gives corporate customers the Input Tax Credit they need, and signals to every customer that you run a serious business.
Here is a practical, step-by-step method to create the right invoice every time.
Step 1: Set up a consistent invoice number series
GST requires a unique, sequential invoice number. A good pattern: INV-YYYY-#### or INV-2526-0001 (financial year + sequence). Never skip, reuse or backdate numbers.
Step 2: Capture customer and vehicle details correctly
Your invoice must include:
- Customer name and billing address
- Customer GSTIN (if they are a registered business)
- Vehicle number, make and model — standard practice for garage bills
- Odometer reading (optional but useful for service history)
Step 3: List services and parts with HSN/SAC codes
Separate services (labour) from parts (goods). Each line item should have:
- Description (e.g. "Engine oil change — 5W30 synthetic, 4L")
- HSN/SAC code — e.g. 998729 for repair service, 2710 for lubricating oil
- Quantity, unit rate, and line total
See our GST rules guide for common HSN/SAC codes used in garages.
Step 4: Apply the correct tax split
This is where most manual bills go wrong. The rule is simple:
- Customer's state = your state → CGST + SGST (each half of the total GST)
- Customer's state ≠ your state → IGST (the full GST amount)
A 18% GST on ₹2,000 becomes ₹180 CGST + ₹180 SGST inside your state, or ₹360 IGST for an out-of-state customer.
Step 5: Show totals and payment terms
Display:
- Taxable value (sum of line items before tax)
- CGST / SGST / IGST split
- Grand total in figures and words
- Payment mode (cash / UPI / card) and any amount due
- Place of supply — the customer's state code
Step 6: Add authorized signature and terms
Include your garage's signature / stamp area and a short terms block — warranty period, return policy for parts, what is not covered.
Common mistakes to avoid
- Hand-written invoice numbers that skip or repeat
- Forgetting the customer GSTIN — they lose Input Tax Credit
- Charging CGST + SGST for a customer from another state
- Skipping HSN/SAC codes on small bills
- Rounding off tax incorrectly (the rule: round the total, not each line)
Mechanic Mate generates every invoice with all required fields, validates GSTINs in real time, picks the right CGST/SGST or IGST split, and maintains a sequential invoice number — no manual bookkeeping needed.
Stop writing invoices by hand
Create professional, GST-compliant bills in seconds with Mechanic Mate.
Get it on Google PlayFrequently asked questions
What must a GST-compliant garage invoice include?
Garage name, address, and GSTIN. Customer details (with GSTIN if registered). Unique sequential invoice number. Invoice date. Vehicle details. Line items with HSN/SAC codes. CGST + SGST or IGST split. Total in words and figures. Place of supply (customer's state code).
What invoice number format should garages use?
Use a unique sequential pattern like INV-YYYY-#### or INV-2526-0001 (financial year + running sequence). Never skip, reuse, or backdate numbers — GST law requires sequential numbering.
How do I split GST correctly on garage invoices?
If the customer is in your state, split the GST as CGST + SGST (each half of total). If the customer is in a different state, charge the full GST amount as IGST. An 18% GST on ₹2,000 becomes ₹180 CGST + ₹180 SGST intra-state, or ₹360 IGST inter-state.
What HSN or SAC code should appear on garage invoices?
For labour and repair services, use SAC 998729. For parts, use HSN codes like 8708 (motor vehicle parts), 2710 (oils), 4011 (tyres). Every line item must have the correct code.