GST Due Date Calculator

Estimate a routine GST due date from return period, due day and extension. Enter your own values below to see due date under the entered schedule and check the method behind it.

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Your inputs

Change the example values to match your situation.

Your result

Let’s work it out.

Fill in your inputs and select Calculate.
Your result and breakdown will appear here.

How this calculator works

Routine due day in the month after the return period, plus the notified extension you enter.

Before you use the result

  • Confirm return frequency, state group and current extensions on https://www.gst.gov.in . This tool does not fetch notifications or determine your filing eligibility.

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What is GST Due Date Calculator?

GST Due Date Calculator helps you estimate a routine GST due date from return period, due day and extension.

The main result is due date under the entered schedule. The formula, example and assumptions below explain how to interpret it.

How to use GST Due Date Calculator

Use the example to get familiar with the form, then enter your own figures. Any rates in the example are illustrative. Check the field labels and units before calculating.

  1. Gather return period ending, return schedule and notified extension (calendar days). Use values from the same situation or reporting period.
  2. Replace the example return period ending with your own value, then complete the other fields. Check the displayed units and each selected option.
  3. Select Calculate and read due date under the entered schedule. Change one input and calculate again to compare a second scenario. Reset restores the original example.
  • Select the return period ending as a calendar date. The example uses 2026-08-31.
  • Choose return schedule from GSTR-1 monthly: next month, day 11, GSTR-3B monthly: next month, day 20, GSTR-1 quarterly: following month, day 13, GSTR-3B quarterly: state group day 22 and GSTR-3B quarterly: state group day 24.
  • Enter notified extension (calendar days), at least 0 and at most 366. Use a whole number.

GST Due Date Calculator: a worked example

With the inputs below, the result is 2026-09-20 (due date under the entered schedule). Follow the example, then replace these illustrative values with your own.

Example inputs and output
Input or outputExample value
Return period ending2026-08-31
Return scheduleGSTR-3B monthly: next month, day 20
Notified extension (calendar days)0
Due date under the entered schedule2026-09-20

Understanding the GST Due Date result

The main output is due date under the entered schedule. It applies to the inputs and operation you selected.

Displayed results use a readable number of decimal places. When checking a result by hand, keep extra precision until the last step. To compare scenarios, change one input at a time and keep the others fixed.

GST Due Date Calculator: assumptions and common mistakes

A useful estimate starts with the right inputs. Check the following assumptions and limits before applying the result to your situation.

  • Confirm return frequency, state group and current extensions on https://www.gst.gov.in . This tool does not fetch notifications or determine your filing eligibility.
  • Check whether endpoints are included and which weekend or holiday settings apply. An entered deadline is not a live notification from an authority.

For wider guidance, visit Government of India calendar. The formula and scope of this specific tool are stated on this page.

GST Due Date Calculator FAQs

What does GST Due Date Calculator calculate?

GST Due Date Calculator helps you estimate a routine GST due date from return period, due day and extension. Its main output is due date under the entered schedule.

What inputs do I need for GST Due Date Calculator?

You need return period ending, return schedule and notified extension (calendar days). Use the field labels and units to match your figures to the formula.

Which formula does GST Due Date Calculator use?

Routine due day in the month after the return period, plus the notified extension you enter.

What is a worked example for GST Due Date Calculator?

Example inputs: Return period ending: 2026-08-31; Return schedule: GSTR-3B monthly: next month, day 20; Notified extension (calendar days): 0. The result is 2026-09-20 (due date under the entered schedule).

How should I enter return period ending?

Select the return period ending as a calendar date. The example uses 2026-08-31.

How do I choose return schedule?

Choose return schedule from GSTR-1 monthly: next month, day 11, GSTR-3B monthly: next month, day 20, GSTR-1 quarterly: following month, day 13, GSTR-3B quarterly: state group day 22 and GSTR-3B quarterly: state group day 24. The example uses GSTR-3B monthly: next month, day 20; replace it if your circumstances differ.

How should I read due date under the entered schedule?

The main output is due date under the entered schedule. It applies to the inputs and operation you selected.

Why might my GST Due Date Calculator result differ from my records?

Confirm return frequency, state group and current extensions on https://www.gst.gov.in . This tool does not fetch notifications or determine your filing eligibility. Differences in entered values, units or rounding can also change the comparison.

Can I compare two scenarios in GST Due Date Calculator?

Yes. Note your first due date under the entered schedule, change return period ending or another input, and select Calculate again. Editing a field clears the old result so it is not mistaken for a new calculation.

Is GST Due Date Calculator free, and where are my inputs calculated?

This calculator is free to use without signing in. Its formula runs in your browser; calculator inputs are not sent to a calculation API. The inputs reset to the example values when you reset the form or start a fresh page.