Key takeaways
What this article covers, in order:
- The month at a glance
- Through the month: record as you go
- Days 1 to 3: close last month
- By the 11th: GSTR-1
- Around the 14th: GSTR-2B and your ITC
- The 15th to 18th: prepare GSTR-3B
It's the 19th, your CA isn't picking up, and GSTR-3B is due tomorrow. You still haven't found two purchase bills, and the portal will be crawling by 9 pm. We've all seen this month. The way out isn't working harder on the 19th; it's spreading the work across the month so the 20th is a non-event. Here's a simple routine for a monthly filer, with notes for QRMP filers, that takes most small businesses two or three short sessions a month.
The month at a glance
| When | What you do | Time it takes |
|---|---|---|
| Daily or weekly | Record sales, purchases, payments as they happen | 10–20 minutes a session |
| 1st–3rd | Close last month's books | 30–60 minutes |
| By the 11th | File GSTR-1 | 15–30 minutes |
| Around the 14th | Review GSTR-2B, reconcile ITC | 30–60 minutes |
| 15th–18th | Prepare GSTR-3B, pay tax | 20–30 minutes |
| By the 20th | File GSTR-3B (aim for the 17th or 18th) | 10 minutes |
| Last week | Chase suppliers, clean up, check notices | 20 minutes |
The figures are rough. A shop with 40 invoices a month will be quicker than a distributor with 400.
Through the month: record as you go
The biggest saver is boring: enter things when they happen. Raise invoices from your system, not a notebook you'll type up later. Photograph or upload purchase bills the day they arrive. Import your bank statement once a week and match receipts and payments.
Pooja runs a small catering business in Ahmedabad. She used to keep bills in a shoebox and sort them on the 18th. Now she spends ten minutes every Saturday entering the week's bills. Her GST "work" dropped from one long, stressful night to a few short sessions. Nothing clever, just regular.
Days 1 to 3: close last month
Before you file anything, make sure last month is actually finished:
- Every sales invoice raised, including that one you promised "next week"
- Credit notes issued for returns or discounts agreed last month
- All purchase bills entered, with supplier GSTIN and the right tax split
- Bank statement imported and matched to the end of the month
- Reverse-charge purchases (advocate fees, some transport and rent) flagged
If you know a bill is missing, note it. You can claim the credit in a later month once it's in hand and in 2B.
By the 11th: GSTR-1
GSTR-1 tells the system what you sold. Before filing, glance over three things.
Are B2B customers showing GSTINs? Any invoice without one will go into B2C, and that customer loses credit.
Do the inter-state invoices carry IGST, and the local ones CGST and SGST?
Are the HSN summary and document summary filled? People skip them.
Then file. Filing GSTR-1 on time matters for your customers too, because their GSTR-2B depends on it. A late GSTR-1 is the fastest way to irritate a good customer.
If you're on QRMP: for the first two months of each quarter you can upload B2B invoices through IFF by the 13th (optional, but your customers will thank you). The full GSTR-1 is due by the 13th after the quarter ends.
Around the 14th: GSTR-2B and your ITC
The portal generates GSTR-2B around the 14th. This is the statement of what credit you can claim for the month, based on your suppliers' filings. Compare it with your purchase register. You'll typically find three kinds of difference.
Some bills are in your books but not in 2B. The supplier hasn't filed, filed late, or used the wrong GSTIN. Don't claim them yet. Send a polite reminder.
Some bills are in 2B but not in your books. Either you're missing a bill, or someone's billed your GSTIN in error. Find out which.
And some amounts don't match. Usually a typing slip or a credit note on one side only. Sort it with the supplier.
Make a short list of who to chase. You'll use it in the last week.
The 15th to 18th: prepare GSTR-3B
Now the summary return. Output tax comes across from GSTR-1, so check it rather than retyping it. Input tax credit should be what's eligible from 2B, less blocked credits (food, personal vehicles, gifts and similar), less anything you have to reverse, such as bills unpaid for more than 180 days.
Add reverse-charge tax, which must be paid in cash.
Work out the cash you need, create a challan on the portal, and pay by net banking, UPI or another permitted mode. Payment can take a little while to reflect, which is one more reason not to leave it to the 20th.
If you're on QRMP: in the first two months of the quarter, pay through PMT-06 by the 25th (either a fixed sum based on past returns or the actual tax due). Your quarterly GSTR-3B is due by the 22nd or 24th after the quarter, depending on your state.
By the 20th: file GSTR-3B
If everything above is done, filing takes ten minutes. Aim for the 17th or 18th. On the evening of the 20th the portal is slow because everyone in the country seems to file at once. We've watched people lose an hour to a spinning wheel.
Filing late means a late fee of ₹50 a day (₹20 for a nil return), subject to caps, plus 18% a year interest on tax paid late in cash.
The last week: tidy up
Use the quiet days. Send your list of missing invoices to suppliers. Check the portal dashboard for intimations about mismatches, since those have a response window. Look at your payables ageing once a quarter for anything approaching 180 days. And note anything unusual from the month (a big advance, a sales return, a new state) so it doesn't surprise you next cycle.
Printable monthly checklist
- [ ] Sales and purchases recorded through the month
- [ ] Bank statement imported and matched
- [ ] Last month's books closed by the 3rd
- [ ] GSTR-1 checked (GSTINs, tax heads, HSN summary) and filed by the 11th
- [ ] GSTR-2B reviewed and reconciled around the 14th
- [ ] Supplier chase list made
- [ ] Blocked credits and reversals removed from ITC
- [ ] Reverse charge added
- [ ] Tax paid by challan
- [ ] GSTR-3B filed by the 20th (target: the 18th)
- [ ] Portal notices checked
- [ ] Supplier reminders sent
If your month has something out of the ordinary, like a big export order, a new branch in another state, or a disputed bill, ask your CA before filing rather than after.
How HelloBooks helps
HelloBooks Free is set up around this exact routine. You record invoices and bills as they happen (on the web or the iOS and Android apps), import your bank statement to match payments, reconcile purchases against GSTR-2B, and file GSTR-1 and GSTR-3B for one GSTIN directly to the GST portal from inside HelloBooks. Before you file GSTR-3B, you'll see the GST portal's own interest and late fee figures, so a late month doesn't turn into a guessing game. Your CA can work in the same books. It's ₹0, no card, no expiry, for up to 200 transactions a year and 2 users. See how GSTR-1 filing, GSTR-2B reconciliation and GSTR-3B filing work.
FAQs
What are the monthly GST due dates for a regular filer?
GSTR-1 by the 11th and GSTR-3B by the 20th of the following month.
When is GSTR-2B available?
Around the 14th of the following month. Reconcile it before preparing GSTR-3B.
What if a supplier's invoice isn't in my GSTR-2B?
Don't claim it yet. Ask the supplier to file, and claim the credit in the month it appears in your 2B.
How do QRMP filers' dates differ?
GSTR-1 quarterly by the 13th after the quarter (with optional IFF by the 13th in months 1 and 2), PMT-06 payment by the 25th in months 1 and 2, and GSTR-3B by the 22nd or 24th after the quarter, depending on state.
How long should monthly GST work take a small business?
If you record as you go, often two or three short sessions a month. Leaving it all to the 19th is what makes it feel huge.
Pick your three dates, put them in your phone, and protect them like customer meetings.
Start free — GST filing included, no card. Try HelloBooks Free
