General information, not professional advice. GST rules, rates and due dates change by notification. Check the current position on the GST Portal or with your CA before you act on anything here.
The short version
- You do not have to wait for 1 April, but you do have to pick a clean cut-off date and hold to it.
- Carry across balances, not history: parties with what they owe, stock with quantities and cost, cash and bank, and any GST position.
- Keep the old system readable until the annual return for that year is filed. Do not cancel it the week you switch.
- Invoice numbering has to stay sequential across the cut-off or you have a Rule 46 problem.
- Run one month in parallel if you possibly can, and reconcile before you stop.
Do you have to wait for April?
The standard advice is to switch at the start of a financial year, and it is good advice, because the year's figures then live in one place and the annual return is straightforward.
It is also advice most people cannot follow, because the reason they are moving is that the present system is failing them now, and eight more months of it is not a plan. A mid-year switch is perfectly doable. It needs a clean cut-off and some discipline about what crosses it.
Pick the cut-off
Choose a date, ideally the first of a month, and treat it as a wall. Everything up to it belongs to the old system. Everything after it belongs to the new one. Nothing gets entered twice, and nothing gets entered in whichever one happens to be open.
The first of a month matters because GST returns are monthly or quarterly. A cut-off in the middle of a tax period means one return has to be assembled from two systems, which is exactly the mess you are trying to avoid.
What to carry across
The instinct is to bring everything. Resist it. You are carrying balances, not history:
| Carry | Why |
|---|---|
| Parties and their balances | Who owes you, who you owe, as at the cut-off. Without these, udhaar restarts at zero and you will chase nobody. |
| Stock, with quantity and cost | Quantity alone is not enough: without cost, the first sale of each item cannot compute a margin. |
| Cash and bank balances | The opening position everything else is measured from |
| Your item and price list | With HSN codes and GST rates, so bills are right from day one |
| Any unclaimed input tax credit | It is money, and it does not travel by itself |
Do not carry every past invoice. They stay in the old system, which is where they are already correct and already filed from.
The invoice numbering trap
This is the one that causes real trouble, and it is easy to miss.
A tax invoice number has to be a consecutive serial for the financial year, unique, and no more than sixteen characters. Switch systems and start again at 001 when your old system reached 847, and you have two invoices numbered 001 in one year.
So: continue the series. Set the new system's next number to carry on from where the old one stopped. If you would rather have a visible break, change the prefix rather than the sequence, so it is still one unbroken run for the year. Note what you did and why, because your CA will ask.
Keeping GST intact
- Close the old period cleanly. File the return for the last full period from the old system before you rely on the new one.
- Do not split a tax period across two systems if you can avoid it.
- Reconcile the cut-off against GSTR-2B once, so any purchase credit sitting unclaimed comes across rather than being lost between systems.
- Check the place-of-supply settings in the new system before the first bill. A wrong default produces CGST and SGST where IGST belonged, and correcting that later means credit notes.
One month in parallel
If you can bear it, enter one month in both. At the end, compare four numbers: total sales, total purchases, closing stock value and the outstanding receivables. If all four agree, the new system is configured correctly. If one does not, you have found the misconfiguration while it is still one month old rather than at the annual return.
It is tedious and almost everybody skips it. The people who skip it are the people who find the problem in December.
What to do with the old system
Keep it readable. GST records have to be kept for 72 months from the due date of the annual return for that year, and if the old system holds part of the year, it holds part of that record.
Before you stop paying for anything: export everything it will give you, in the most open format it offers, and check the export actually opens. A subscription that lapses with your data inside it is a genuinely bad day. If the software is desktop, take a copy of the data file and keep it somewhere that is backed up.
Do not cancel in the same week you switch. Give it until the annual return for that year is filed.
Bring your balances, not a year of typing
Opening balances for parties, stock and cash can be imported, and every row is previewed before anything is written.
Frequently asked questions
Can I change accounting software in the middle of a financial year?
Yes. Pick a clean cut-off, ideally the first of a month so a GST period is not split across two systems, carry opening balances rather than full history, and keep the old system readable until that year's annual return is filed.
What do I need to carry across?
Balances, not history: parties with what they owe and are owed, stock with both quantity and cost, cash and bank balances, your item list with HSN codes and rates, and any unclaimed input tax credit. Past invoices stay where they are.
What happens to my invoice numbers?
Continue the series. A tax invoice number must be a consecutive serial for the financial year, unique and at most sixteen characters, so restarting at 001 mid-year creates duplicates. If you want a visible break, change the prefix rather than the sequence.
Should I run both systems in parallel?
For one month if you can. At the end compare total sales, total purchases, closing stock value and outstanding receivables. If all four agree the new system is configured right; if one does not, you have found it while it is a month old.
When can I stop paying for the old software?
After the annual return covering that period is filed, and not before you have exported everything and confirmed the export opens. GST records must be kept for 72 months from the due date of that year's annual return.
Will I lose my history if I switch?
Only if you let the old system go before exporting. The history stays there and remains valid; what moves to the new system is the position as at the cut-off.