When to switch accounting software: 1 April or mid-year

What is a cut-over date?

A cut-over date is the day your new accounting software becomes the only place where new transactions are recorded. Everything before that date stays in the old system as the archive. Everything from that date onwards goes into the new one, starting from opening balances.

The line has to be sharp. A bill dated the day before belongs in the old system, even if it arrives a week later. Most switching problems come from a blurred line, not from the date.

Is 1 April the best day to switch accounting software?

1 April is the cleanest day to switch because the financial year, the invoice series and the GST registers all start fresh on the same day. Your old system holds one complete year and your new system starts the next one.

• One year, one system. The profit and loss for the closed year comes from the old software alone, and the new year from the new software alone.
• One GST register set per system per year. The sales and purchase registers your accountant checks for returns come from one place for each month.
• Numbering restarts cleanly. A fiscal-year series such as INV-2026-27-0001 begins at 0001 on 1 April anyway, so there is no gap or overlap to explain.
• Opening balances are year-end balances. The closing trial balance at 31 March is usually reviewed by your accountant already.

The cost of waiting is real, though. In October, waiting for April means six more months of an old setup that is already failing you.

Can you switch accounting software in the middle of the year?

Yes, a mid-year switch is safe if you cut over on the first day of a month, take a trial balance on the last day of the previous month, and keep both systems' GST registers for the split period. The extra work is mostly for your accountant at year end.

The first day of a month matters because GST returns are prepared month by month. If you switch on 1 October, September sits entirely in the old system and October entirely in the new one. Switch on 17 October and the October returns need two registers added together.

Which cut-over date suits your business?

The right date depends on how much the old system is costing you now and how much year-end work a split year adds. Use this table with your accountant.

What does a mid-year cut-over look like with real numbers?

Lakshmi Steel Furnitures, the fictional Coimbatore business on this site, decided in September 2026 not to wait for April. It chose 1 October 2026 as the cut-over date and took this trial balance from Tally at the close of 30 September.

Every line becomes an opening balance on 1 October. Customer and supplier totals go in party by party, so each statement of account opens with the right balance. Stock goes in by product with quantity and cost. Reserves and profit of ₹2,35,600 sit in equity as one opening figure; the detailed profit and loss for April to September stays in Tally, which is the archive for those six months.

1. 1

   30 September, evening: close the old system

   Post the last invoices and bills, count stock, and take the trial balance, receivables and payables by party, and the September GST registers.

2. 2

   1 October: enter opening balances

   Enter every trial balance line, with parties and products in detail, and check the new trial balance matches.

3. 3

   1 October: freeze the old period

   Once the figures match, set a lock date of 30 September in the new system.

4. 4

   1 to 14 October: dry run

   Raise each real invoice in both systems and compare the totals each week.

5. 5

   15 October: go live

   Stop all entries in the old system and keep it read-only as the archive.

What does your CA need for each choice?

Your accountant needs a trial balance at the cut-over date and the GST registers from whichever system held each month.

• The cut-over date is the 1st of a month and written down
• The old system's trial balance at the day before cut-over balances
• Receivables and payables add up to the control accounts in that trial balance
• Stock counted, and its value matches the inventory line
• GST registers for every month before cut-over exported from the old system
• The new system's trial balance after opening balances matches the old one line for line
• A lock date set at the day before cut-over
• The old system kept, read-only, as the archive

Why does a lock date matter after you switch?

A lock date freezes every period up to that date, so nobody can post a backdated entry into a month you have already handed to your accountant. After a cut-over, it protects the opening balances: once they are agreed, they cannot move.

Without one, a late bill dated 28 September can be entered in the new system and quietly change a September figure that came from Tally. Set the lock date to the day before cut-over as soon as the opening balances match.

Why does invoice numbering restart cleanly on 1 April?

Invoice numbers must be unique within a financial year, so a series that carries the year in it restarts at 0001 every 1 April without clashing with last year. A number such as INV-2026-27-0001 is 16 characters, within the limit for a tax invoice number.

On a 1 April switch, the new system simply starts the new year's series. On a mid-year switch, agree the next number with your accountant so the series continues without a gap or a duplicate, or start a separate series for the rest of the year.

How does SimpleERP handle either cut-over date?

SimpleERP has an opening balances wizard that takes the trial balance per account, and receivables and payables per party, with any difference going to Opening Balance Equity. Opening stock goes in by product, by stock adjustment or by import. Customers, suppliers, balances and open bills can be imported from Tally or a spreadsheet, dated by the cut-over. One accounting lock date then freezes the old period.

• Fiscal-year invoice numbering such as INV-2026-27-0001, which restarts on 1 April.
• Sales and purchase registers for the months in SimpleERP, to sit beside the old system's registers.
• Trial balance, profit and loss and balance sheet, each with CSV export for your CA.

Read more on the moving from Tally or Excel page, or see how SimpleERP compares with Tally.