How to Create a GST-Compliant Invoice for Your Garage

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.