GSTRate changeTatva ERP
When GST rates change overnight: what has to happen inside your billing software
The September 2025 rate revision moved thousands of items between slabs. Here is the work it creates in a shop's software, the order to do it in, and the one master that should make it a five-minute job.
- Author
- Kentron Technologies
- Published
- Reading time
- 5 min read
When the GST Council revises rates, the work lands in three places on the same night: the item masters in your software, the price tags on your shelves, and the bills you are about to print. The revision of 22 September 2025 was the largest of these in years, collapsing the 12 per cent and 28 per cent slabs so that most goods sit at 5 or 18 per cent, with a 40 per cent rate for a short list. Shops that had the rate stored on each item individually spent days on it. Shops that had it stored on the HSN spent an evening.
What has to change, in order
- The rate on the HSN master, from the effective date. This is the single fact; everything else should follow it.
- The items under that HSN, pushed in bulk rather than opened one by one.
- Open quotations and pending orders priced at the old rate, which have to be re-priced or honoured knowingly.
- Shelf labels and price tags, if you display prices inclusive of tax.
- The printed bill format, if it shows a rate-wise tax summary, so the new slabs appear correctly.
- Your own selling price, which is a business decision and not an automatic one: a rate cut can be passed to the customer, absorbed, or split.
In Tatva ERP the HSN is a master of its own. It carries the GST rate, and changing it offers to push the new rate to every item mapped to that HSN. A pharmacy with four thousand item codes across thirty HSNs changes thirty things, not four thousand.
Stock bought at the old rate
The two questions every owner asks on rate-change night are whether old stock must be sold at the old rate, and whether the credit already claimed on it has to be given back.
- The rate you charge is the rate in force at the time of supply, determined by the date of invoice, the date of supply and the date of payment under section 14 of the CGST Act. For an ordinary counter sale on the day after the change, that means the new rate, whatever you paid on purchase.
- Input tax credit already correctly claimed on stock in hand is not reversed because the output rate changed. It is still your credit.
- Where a rate cut leaves accumulated credit that cannot be used, the position is more involved and depends on the sector. That is a question for your accountant, not for your billing software.
- Goods sold before the change and returned after it come back with the rate on the original invoice, through a credit note linked to that invoice.
That last point is the one software gets wrong most often. A credit note that picks up today's rate instead of the rate on the original bill creates a difference that shows up in the return, not on the counter. Check it deliberately in the first week after any revision.
MRP and price tags
For packaged goods, the printed maximum retail price is governed by legal metrology rules, not by GST. After past revisions, government has permitted revised prices to be declared by sticker, stamp or online print for a stated period, alongside the original MRP, with the change advertised. Check the notification that accompanies each revision before restickering, and keep a copy of it with your stock records.
Inside the software, the practical need is different: the MRP on the item or the batch has to be changeable per batch, so that old stock and new stock can sit on the same shelf with the prices they were actually packed with. Batch-wise MRP is a routine requirement for pharmacy and FMCG, and is covered in batch and expiry billing.
A checklist for the night of a revision
| Step | Who | Done when |
|---|---|---|
| Read the official notification, not a forward | Owner or accountant | You can name the notification number |
| List the HSNs you sell and their new rates | Accountant | One sheet, every HSN in your catalogue |
| Update the HSN masters and push to items | Whoever maintains masters | A sample of ten items shows the new rate |
| Test one bill per slab | Billing staff | Tax figures and the rate-wise summary are right |
| Re-price shelf tags and pending quotations | Store staff | No tag shows a price you can no longer honour |
| Check a credit note against an old invoice | Accountant | It uses the old rate |
| File the month's return and reconcile | Accountant | Register and GSTR-1 agree |
What to ask a vendor about rate changes
Ask three questions. Is the rate stored on the HSN or on each item? Can it be changed in bulk with an effective date? And does a credit note against an older invoice use the rate on that invoice? A vendor whose answer to the first is per item will quietly cost you a day of work every time the Council meets. Rate changes are also the clearest argument for keeping the software under a live maintenance contract, which is discussed in what billing software costs.
Frequently asked questions
What are the current GST slabs?
Since 22 September 2025 the main rates are nil, 5 per cent and 18 per cent, with 40 per cent on a short list of luxury and sin goods; the earlier 12 and 28 per cent slabs were largely folded into the two main ones. Rates for individual goods change from time to time, so confirm a specific item against the notification or the rate finder on the GST portal rather than from memory.
Do I have to sell old stock at the old GST rate?
No. The rate charged is the one in force at the time of supply under section 14, so a sale made after the change carries the new rate even if the goods were bought before it. What you paid at purchase stays as input tax credit.
How do I change the GST rate for all items at once?
Through the HSN master, if your software has one. Set the new rate against the HSN and push it to every item mapped to it, then spot-check ten items and print one test bill per slab. Editing four thousand item masters by hand is how a wrong rate reaches a real invoice.