Common GST Billing Mistakes and How ERP Prevents Them

GST Mistakes Are Costly — And Common

Even experienced businesses make GST billing mistakes. Most are unintentional — wrong rate applied, wrong GSTIN entered, ITC not claimed. But the GST department doesn't differentiate between intentional and accidental errors. Penalties apply regardless.

10 Most Common GST Billing Mistakes

Mistake 1: Wrong GST Rate Applied

Many products have different GST rates — and rates change. Applying 12% instead of 5% or 18% instead of 12% is common.
ERP Fix: HSN code-linked tax rates auto-update. The ERP always applies the current correct rate.

Mistake 2: Missing Customer GSTIN on B2B Invoice

B2B invoices must include the buyer's GSTIN for ITC purposes. Missing GSTIN means your customer can't claim ITC — leading to disputes.
ERP Fix: Customer master stores GSTIN. If missing, ERP alerts before invoice generation.

Mistake 3: CGST/SGST vs IGST Confusion

For intra-state: CGST + SGST. For inter-state: IGST. Mixing these up is a common error.
ERP Fix: ERP checks customer's state automatically and applies the correct tax type.

Mistake 4: Not Recording Purchase Invoices

Every unrecorded purchase invoice = missed ITC.
ERP Fix: Systematic purchase entry workflow ensures every supplier invoice is recorded and ITC captured.

Mistake 5: Wrong HSN Code

GSTR-1 requires correct HSN codes. Wrong codes trigger mismatches and department inquiries.
ERP Fix: Product master with pre-configured HSN codes ensures every bill has the right code.

Mistake 6: Sales Return Not Adjusted

Returns need a credit note that must be reflected in GSTR-1. Ignoring this creates return filing errors.
ERP Fix: Credit note workflow automatically adjusts GST liability and GSTR-1 summary.

Mistake 7: Rounding Errors

Manual calculations lead to rounding mismatches between invoice total and GST amount.
ERP Fix: Digital calculation with proper rounding logic — every time, without exception.

Mistake 8: Not Filing on Time

Late filing fees: ₹50/day (₹20 for nil returns). Plus 18% interest on unpaid tax.
ERP Fix: One-click GSTR report generation means you're always ready to file on time.

Mistake 9: Missing E-Invoice for Eligible Businesses

Businesses above ₹5 crore must generate e-invoices. Missing this is a compliance violation.
ERP Fix: MILAAN ERP generates IRN automatically for all eligible invoices.

Mistake 10: Duplicate Invoice Numbers

GSTR-1 doesn't allow duplicate invoice numbers. Manual billing often creates duplicates.
ERP Fix: ERP auto-generates sequential unique invoice numbers — duplicates are impossible.

MILAAN ERP: Your GST Error Shield

• Auto correct GST rate from HSN codes
• GSTIN validation for all customers
• Auto CGST/SGST vs IGST based on customer state
• ITC tracking for every purchase
• E-invoice IRN generation
• Unique sequential invoice numbering