GSTR-1 and GSTR-3B: A Simple Guide to Your Monthly GST Returns
Confused between GSTR-1 and GSTR-3B? Here is what each GST return is for, how they connect, and when they are due — explained in plain language.
Every GST-registered business files returns regularly, and the two you will deal with most are GSTR-1 and GSTR-3B. They sound similar but do quite different jobs. Here is the plain-language version.
Two returns, two jobs
Think of it this way: one return describes your sales in detail, the other summarises everything and collects the tax.
What is GSTR-1?
GSTR-1 is your statement of outward supplies — a detailed list of every sale you made in the period. B2B sales are reported invoice by invoice; B2C sales are summarised.
There is an important knock-on effect: the data you file in GSTR-1 flows into your customers' GSTR-2B. That is how they receive input tax credit on what they bought from you. So filing GSTR-1 accurately and on time is not only your compliance — it directly affects your customers' credit.
What is GSTR-3B?
GSTR-3B is your summary return and tax payment. In it you declare, in summary form:
- your total outward supplies,
- the input tax credit you are claiming, and
- the net GST you actually have to pay.
The tax is paid when you file GSTR-3B. No GSTR-3B, no payment recorded.
How the two connect
- GSTR-1 = the detail of what you sold.
- GSTR-3B = the summary, plus the payment.
The two must tell a consistent story. The GST system increasingly auto-populates parts of GSTR-3B from your GSTR-1 and GSTR-2B, and mismatches between them are a common trigger for notices.
When are they due?
For monthly filers (turnover above ₹5 crore, and others who opt for monthly filing):
- GSTR-1 — by the 11th of the following month.
- GSTR-3B — by the 20th of the following month.
Smaller businesses (turnover up to ₹5 crore) can opt for the QRMP scheme — filing GSTR-1 and GSTR-3B quarterly while paying tax monthly. QRMP due dates are different. Always confirm the exact date on the GST portal, as deadlines are sometimes extended by notification.
What happens if you file late
Late filing attracts a late fee per day plus interest on any unpaid tax. There is also a sting in the tail: you cannot file the current period until the previous one is filed. Returns must go in sequence, so one missed return blocks every return after it.
Make returns a non-event
The hard part of GST returns is not the filing — it is keeping the underlying data correct all month. If every invoice carries the right GST rate and HSN code as you raise it, GSTR-1 becomes a simple summary of data that is already clean.
That is how Booksmor works: GST-ready data is captured from every transaction, so your returns are built from accurate books — not assembled in a month-end scramble. Start a 30-day free trial and take the stress out of return season.