Free GST tools and due dates for small businesses

Independent, not the government GST portal. For small businesses in India.

Looking for the GST login? The official portal is gst.gov.in.

GST tools

They work on your own phone or computer, and what you type isn’t sent anywhere.

GST calculator
Add GST to a price, or find the GST in a price. See the CGST and SGST, or IGST.
Late fee and interest calculator
Work out the late fee for a GSTR-3B or GSTR-1 filed after its due date, and the interest on GST paid late.
GSTIN checker
Check a GSTIN for typing mistakes before you put it on an invoice. It can’t tell you if the business is registered.
GST due dates
Upcoming GST due dates, and a way to add them to your calendar app.

The next dates for the main returns, as of 30 Oct 2026:

Wed, 11 Nov 2026GSTR-1 for Oct 2026For monthly filersSource: Notification No. 83/2020-Central Tax
Fri, 20 Nov 2026GSTR-3B for Oct 2026For monthly filersSource: rule 61 of the CGST Rules (the link opens CBIC’s tax information site: open GST, then Rules)
Wed, 25 Nov 2026PMT-06 for Oct 2026 (tax payment)For QRMP filersSource: rule 61 of the CGST Rules (the link opens CBIC’s tax information site: open GST, then Rules)

Sources last checked: 28 Oct 2026

Not sure which dates are yours? The due dates page has them for monthly filers, quarterly (QRMP) filers and the composition scheme.

Not the government portal: gstindia.com is independent. It isn’t run or approved by the Government of India, the GST Network (GSTN) or the Central Board of Indirect Taxes and Customs (CBIC). To file a return or pay tax, go to gst.gov.in.
Every number has a source: Every rate, fee and due date we show links to the official source it comes from (the GST law, a notification or an advisory), with the date we last checked it. If we can’t check a number, we leave it out, or say plainly that it isn’t confirmed yet.
What you type stays with you: Our tools work on your own phone or computer. What you type into them, such as amounts and GSTINs, isn’t sent to us or saved.
Free, with no sign-up: You don’t need an account to use the tools.