Why do I need a new invoice series each financial year?

GST Rule 46(b) requires invoice numbers to be unique within a financial year. Starting a fresh series from April 1 ensures compliance and prevents duplicate invoice numbers across years.

How do I set up a new invoice series in TallyPrime?

Go to Gateway of Tally > Alter > Voucher Types > Sales. Update the voucher numbering method, set the starting number to 1, and optionally add a prefix like '2627/' to indicate the financial year.

What is the maximum length for GST invoice numbers?

GST invoice numbers can be up to 16 characters alphanumeric. This includes any prefix or suffix you use. For example: 'MARK/2627/0001' is 14 characters and compliant.

Should I use prefixes or suffixes for the financial year?

Using a financial year prefix (like 2627/ for FY 2026-27) is recommended as it makes invoices easily identifiable by year and prevents any confusion with previous years' invoices.

What about other voucher types like credit notes?

Reset all voucher series including Credit Notes, Debit Notes, Receipt Vouchers, and Payment Vouchers. Each should have unique numbering within the financial year following the same pattern.

New Invoice Series for April 2026: TallyPrime Setup Guide

Every financial year, GST-registered businesses in India must reset their invoice numbering series to comply with Rule 46(b) of the CGST Rules 2017. As FY 2026-27 begins on April 1, 2026, your business needs to initiate a fresh invoice series with unique 16-character alphanumeric numbers distinct from the previous year. This isn't just a compliance formality - incorrect invoice numbering can cause e-Way Bill generation failures, GSTR-1 filing issues, and refund claim rejections. This comprehensive guide explains the legal requirements, best practices, and step-by-step TallyPrime configuration for seamless invoice series transition.

Legal Requirement: Why Invoice Series Must Reset

Rule 46(b) CGST Rules 2017: Mandates unique 16-character alphanumeric invoice numbers for each financial year
Uniqueness requirement: Invoice numbers must not duplicate within or across financial years
Sequential numbering: Invoices must follow non-duplicative, sequential order
No mid-year reset: Invoice series should not restart during the financial year
Document type distinction: Separate series for invoices, credit notes, debit notes, bills of supply
Multiple series allowed: Businesses with branches/divisions can maintain multiple series if clearly identifiable

Consequences of Non-Compliance

E-Way Bill generation failure: System rejects invoices with improper numbering
GSTR-1 filing issues: Portal flags duplicate or improperly formatted invoice numbers
Refund claim rejection: GST refund applications fail due to invoice irregularities
IRP rejection: E-invoicing system rejects invoices not meeting Rule 46 requirements
Audit red flags: Non-compliant invoicing attracts scrutiny during GST audits
Compliance notices: Risk of show-cause notices and penalties

Best Practices for Invoice Numbering

Use financial year prefix: Format like /26-27/ or -2627- to clearly distinguish years
Example: INV/26-27/0001, SALE-2627-0001
Avoid restricted characters: Don't start invoice numbers with 0, /, or - (rejected by IRP)
Case-insensitive handling: From June 2025, IRP converts all invoice numbers to uppercase (abc101 becomes ABC101)
Plan for volume: Ensure sufficient digits for expected invoice count (e.g., 5 digits for up to 99,999 invoices)
Branch identification: Include branch code if maintaining separate series (e.g., INV/MUM/26-27/0001, INV/DEL/26-27/0001)
Document type codes: Use prefixes like SI (Sales Invoice), CN (Credit Note), DN (Debit Note)

TallyPrime Invoice Series Configuration: Step-by-Step

Step 1: Navigate to Gateway of Tally > F11: Features > F1: Accounts Features
Step 2: Under 'Voucher Entry' section, locate 'Use Voucher Class'
Step 3: Go to Gateway of Tally > Voucher Type > Alter > Select 'Sales'
Step 4: In Numbering section, set 'Method of Voucher Numbering' to 'Automatic'
Step 5: Set 'Starting Number' to 1 (or desired starting point)
Step 6: Update 'Current Year Prefix' field to /26-27/ or -2627-
Step 7: Optional: Set 'Next Year Prefix' to /27-28/ for future readiness
Step 8: Test the setup: Create a sample invoice and verify numbering format
Step 9: Repeat for other voucher types: Purchase, Credit Note, Debit Note, Sales Return

Handling Multiple Invoice Series in TallyPrime

Use Voucher Classes: Create separate voucher classes for different branches/product lines
Example setup: Create 'Sales - Mumbai' and 'Sales - Delhi' voucher types
Configure unique prefixes: Mumbai (INV/MUM/26-27/), Delhi (INV/DEL/26-27/)
Assign to users: Restrict voucher classes to specific users or locations
Maintain consistency: Ensure each series follows sequential numbering without gaps

Transitioning from FY 2025-26 to FY 2026-27

Last invoice of FY 2025-26: Complete all pending March 2026 invoices before series reset
Cut-off date: March 31, 2026 is the last date for FY 2025-26 invoice series
First invoice of FY 2026-27: Must use new series starting April 1, 2026
Year-end reconciliation: Verify last invoice number of old series before resetting
Update TallyPrime: Implement new series configuration before April 1, 2026
Communicate changes: Inform sales team, accounts staff, and customers about new invoice format
Test thoroughly: Generate test invoices in March 2026 to validate new series setup

E-invoicing Considerations

IRP validation: New invoice series must comply with e-invoicing numbering rules
No restricted characters: Avoid starting with 0, /, - as IRP rejects these
Case-insensitive: IRP converts invoice numbers to uppercase (effective June 2025)
Unique IRN generation: Each invoice number generates unique Invoice Reference Number (IRN)
Testing required: Generate test e-invoice with new series before April 1, 2026
Bulk e-invoicing: Ensure TallyPrime bulk IRN generation works with new series

Common Mistakes to Avoid

Mistake 1: Continuing previous year's invoice series into new FY (violates Rule 46)
Mistake 2: Using duplicate invoice numbers across financial years
Mistake 3: Starting invoice numbers with 0 or special characters
Mistake 4: Mid-year series reset causing numbering gaps
Mistake 5: Not updating TallyPrime voucher type settings before April 1
Mistake 6: Using inconsistent formats across different invoice types
Mistake 7: Not testing new series before go-live date

Checklist for April 1, 2026 Readiness

1. Update TallyPrime voucher numbering for all invoice types
2. Set financial year prefix to /26-27/ or equivalent
3. Test invoice generation with new series
4. Verify e-invoicing IRN generation with new series
5. Generate sample e-Way Bill with new invoice number
6. Train accounts and sales teams on new invoice format
7. Update invoice templates (if using custom formats)
8. Communicate changes to key customers and suppliers
9. Prepare FAQ document for customer queries
10. Monitor first week of April 2026 for any issues

Troubleshooting Common TallyPrime Issues

Issue: New series not reflecting in invoices - Solution: Check F11 settings and voucher type configuration
Issue: Old series continuing in April - Solution: Verify 'Current Year Prefix' field is updated
Issue: E-invoicing fails with new series - Solution: Ensure no restricted characters, test IRP connectivity
Issue: Multiple users seeing different invoice numbers - Solution: Synchronize TallyPrime data across users
Issue: Invoice numbering gaps - Solution: Check for deleted/cancelled vouchers, adjust starting number if needed

Need help configuring invoice series in TallyPrime or ensuring compliance for FY 2026-27? Mark IT Solutions provides TallyPrime customization, voucher type configuration, and comprehensive training. Our Tally experts can set up your invoice series, test e-invoicing workflows, and ensure smooth transition to the new financial year. Schedule a consultation today.