How to File GSTR-3B: Step-by-Step Guide with Example

Knowing how to file GSTR-3B correctly is the single most important monthly GST skill for any registered business in India. GSTR-3B is the summary return in which you declare your outward tax liability, claim input tax credit (ITC) and actually pay the net tax. Unlike GSTR-1, which reports invoices, GSTR-3B is where the money moves, so an error here directly affects your cash, your interest exposure and the notices you may receive later. This guide explains every table, walks through a complete worked example with real numbers and lists the checks a careful accountant runs before pressing the file button.

What GSTR-3B is and who must file it

GSTR-3B is a self-declared summary return. Every normal taxpayer registered under GST must file it, including those with nil activity in a period. Composition taxpayers, Input Service Distributors, non-resident taxpayers, TDS deductors and TCS collectors file different returns and do not file GSTR-3B.

There are two filing frequencies:

Monthly filers file GSTR-3B for each month, generally by the 20th of the following month.
QRMP filers (taxpayers with aggregate turnover up to ₹5 crore who opt for the Quarterly Return Monthly Payment scheme) file GSTR-3B every quarter, by the 22nd or 24th of the month after the quarter depending on their state, and pay tax monthly through challan PMT-06.

Due dates are sometimes extended by notification, so always confirm the current date on the GST portal before planning your close. If you are deciding between the two frequencies, our comparison of QRMP versus monthly filing covers the trade-offs.

Before you start: data you need ready

GSTR-3B is quick to file when the underlying data is clean and painful when it is not. Before logging in, collect:

Sales register for the period, split into intra-state and inter-state supplies, taxable, zero-rated, nil-rated, exempt and non-GST supplies.
GSTR-1 or IFF filed for the same period, because Table 3 of GSTR-3B is auto-populated from it.
GSTR-2B for the period, generated after your actions in the Invoice Management System (IMS), because Table 4 is auto-populated from it.
Purchase register reconciled with GSTR-2B, so you know which credits are eligible, which are blocked and which must be reversed.
Reverse charge purchases such as legal fees, goods transport agency services or import of services.
Electronic cash and credit ledger balances, to see whether you need to deposit cash before offsetting.

GSTR-3B table by table

The form looks short, but each table has a specific purpose. The table below summarises what goes where.

Table	What it captures	Source
3.1(a)	Outward taxable supplies (other than zero-rated, nil-rated and exempt)	Auto-filled from GSTR-1/IFF
3.1(b)	Zero-rated supplies: exports and supplies to SEZ	Auto-filled from GSTR-1
3.1(c)	Nil-rated and exempt supplies	Auto-filled from GSTR-1
3.1(d)	Inward supplies liable to reverse charge	Partly from GSTR-2B, verify against books
3.1(e)	Non-GST outward supplies (for example alcohol for human consumption)	Auto-filled from GSTR-1
3.1.1	Supplies made through e-commerce operators who pay tax under section 9(5)	Auto-filled from GSTR-1
3.2	Inter-state supplies to unregistered persons, composition taxpayers and UIN holders, state-wise	Auto-filled from GSTR-1
4A	ITC available: imports, RCM, ISD and all other ITC	Auto-filled from GSTR-2B
4B	ITC reversed: permanent reversals (rule 38, 42, 43, section 17(5)) and temporary reversals	Entered by you
4D	Ineligible ITC, including ITC restricted by place of supply rules	Entered by you
5	Exempt, nil-rated and non-GST inward supplies	Entered by you
5.1	Interest and late fee	System computed, editable in some cases
6.1	Payment of tax: set-off from credit ledger and cash ledger	Computed on the portal

Auto-population and the move to locked values

The GST Network has been steadily making auto-populated values in GSTR-3B less editable. Liability in Table 3 flows from GSTR-1 and GSTR-1A, and the direction of travel is that you correct a mistake at the source (by amending through GSTR-1A or the next GSTR-1) rather than by overriding the number in GSTR-3B. Check the latest portal advisory for the current status of hard-locking before you plan to edit any auto-filled figure.

How to file GSTR-3B on the GST portal: step by step

Log in at the GST portal with your username, password and the second authentication factor (OTP). Multi-factor authentication is now standard for return filing.
Go to Services, then Returns, then Returns Dashboard. Select the financial year, the quarter and the period, then click Search.
Open GSTR-3B by clicking Prepare Online. Answer the initial questions; for a nil return the portal offers a simplified flow, including filing through SMS.
Review Table 3.1 and 3.2. Compare each figure with your sales register. If GSTR-1 had an error, correct it through GSTR-1A before filing GSTR-3B where the window allows.
Review Table 4. Confirm that ITC in 4A matches your reconciled GSTR-2B. Enter reversals in 4B and ineligible ITC in 4D.
Fill Table 5 for exempt and non-GST purchases.
Check Table 5.1 for any interest or late fee computed by the system.
Save and click Proceed to Payment. The portal shows tax payable, ITC available and the cash required.
Create a challan (PMT-06) if your cash ledger is short, and pay through net banking, UPI, card or over-the-counter options shown on the portal.
Offset liability by clicking Make Payment / Post Credit to Ledger, then file with DSC or EVC. Download the filed return and the payment acknowledgement for your records.

Worked example: computing and paying GSTR-3B

Consider a trader registered in Maharashtra with these figures for the month. All supplies are taxed at 18%.

Item	Taxable value	IGST	CGST	SGST
Intra-state sales (within Maharashtra)	₹10,00,000	0	₹90,000	₹90,000
Inter-state sales (to Karnataka)	₹4,00,000	₹72,000	0	0
Total output liability	₹14,00,000	₹72,000	₹90,000	₹90,000
Eligible ITC as per GSTR-2B		₹50,000	₹40,000	₹40,000

Intra-state tax at 18% splits into 9% CGST and 9% SGST: 9% of ₹10,00,000 is ₹90,000 each. Inter-state tax is 18% IGST: 18% of ₹4,00,000 is ₹72,000.

Applying the set-off order

The law requires IGST credit to be used first, against IGST liability and then against CGST and SGST. CGST credit can be used against CGST and IGST but never against SGST, and SGST credit can be used against SGST and IGST but never against CGST. In our example:

IGST credit of ₹50,000 is used against IGST liability of ₹72,000. Balance IGST payable in cash: ₹22,000.
CGST credit of ₹40,000 is used against CGST liability of ₹90,000. Balance CGST payable in cash: ₹50,000.
SGST credit of ₹40,000 is used against SGST liability of ₹90,000. Balance SGST payable in cash: ₹50,000.

Total cash payable is ₹22,000 + ₹50,000 + ₹50,000 = ₹1,22,000. As a cross-check, total liability of ₹2,52,000 less total ITC of ₹1,30,000 also equals ₹1,22,000. If the trader also had reverse charge liability, that portion would have to be paid in cash only, because ITC cannot be used to discharge reverse charge tax.

Reverse charge, reversals and ineligible credit

Three areas cause most GSTR-3B corrections:

Reverse charge

Report RCM purchases in Table 3.1(d), pay the tax in cash, and then claim the same amount as ITC in Table 4A(3) in the same return if the purchase is used for business and is not blocked. Common examples are legal fees paid to advocates, freight paid to goods transport agencies that have not opted for forward charge, and imported software or advertising services.

Reversals in Table 4B

Table 4B(1) is for permanent reversals such as rule 42 and 43 common credit reversals and blocked credits under section 17(5). Table 4B(2) is for temporary reversals that you may reclaim later, such as ITC reversed because you did not pay a supplier within 180 days. Reclaimed amounts go back in Table 4A(5) and should also be shown in Table 4D(1) as reclaimed, so the electronic credit reversal and reclaimed statement on the portal stays in balance.

Ineligible ITC in Table 4D

Table 4D(2) captures ITC restricted under the place of supply rules, for example hotel stays in another state billed with that state's CGST and SGST, which you cannot use in your home state.

Late fee and interest at a glance

Filing late attracts a late fee for each day of delay (with a lower rate for nil returns and caps linked to turnover), and interest at 18% per annum on the tax paid late in cash. Interest is calculated on the net cash liability, not on the gross tax, because ITC available in the credit ledger is not treated as tax paid late. If you want to compute both, see our guide to GST late fee and interest calculation.

Common GSTR-3B mistakes to avoid

Claiming ITC that is not in GSTR-2B. Since the introduction of section 16(2)(aa), credit is available only if the invoice appears in your GSTR-2B.
Mismatched liability between GSTR-1 and GSTR-3B. If Table 3 liability is lower than GSTR-1 beyond a tolerance, the portal can issue an intimation in DRC-01B and may block GSTR-1 filing for the next period until you respond.
ITC claimed higher than GSTR-2B. Excess ITC beyond tolerance can trigger DRC-01C.
Paying RCM through credit ledger. Reverse charge tax must be paid in cash.
Ignoring rule 37 reversals for unpaid suppliers older than 180 days.
Reporting exports without LUT details or wrong tables. Exports without tax go in 3.1(b), not 3.1(c).
Not saving the filed copy and challan. Auditors and officers will ask for them.

Pre-filing checklist

GSTR-1 or IFF for the period filed, and any GSTR-1A amendment done.
IMS actions completed and GSTR-2B regenerated if you changed any action.
Purchase register reconciled with GSTR-2B and differences documented.
Blocked credits and common credit reversals computed.
RCM liability computed and cash available.
Cash ledger topped up with a PMT-06 challan if needed.
Sales register total equals Table 3.1 plus 3.1.1 totals.
Filed return and challan saved in the compliance folder.

How Fininvo helps with GSTR-3B

When tax is calculated correctly on each invoice and bill, GSTR-3B becomes a review exercise rather than a reconstruction. Fininvo ERP calculates CGST, SGST and IGST on every transaction, generates GSTR-3B data from your books and reconciles purchases against GSTR-2A/2B so that mismatches are flagged before you file. See tax and compliance features, GST reports or pricing to explore further.

This article is general information, not tax advice. Rules, forms and due dates change through CBIC notifications and GSTN advisories; consult your CA before acting.

Frequently Asked Questions

Can I revise GSTR-3B after filing?

No. GSTR-3B cannot be revised once filed. Errors are corrected in the return of a later period, within the time limits set by the law, or by paying additional tax through DRC-03 where appropriate. Errors in liability that came from GSTR-1 are best corrected through GSTR-1A or a later GSTR-1 amendment.

Do I need to file GSTR-3B if there were no sales?

Yes. A nil GSTR-3B must be filed for every period while your registration is active. Nil returns can be filed online with a simplified flow or by SMS, and a lower late fee applies if you miss the date.

Why is my GSTR-3B Table 4 different from my purchase register?

Table 4 is auto-filled from GSTR-2B, which only includes invoices your suppliers reported by their cut-off date and that you did not reject in IMS. Invoices reported late by suppliers will appear in a later GSTR-2B, and you can claim them in that period.

Can CGST credit be used to pay SGST?

No. CGST credit can be used only against CGST and IGST liability, and SGST credit only against SGST and IGST. IGST credit must be fully used first before CGST and SGST credit are used.

What happens if I file GSTR-3B but do not pay the tax?

The return cannot be filed until the liability shown is offset, so you must deposit cash in the electronic cash ledger first. If you cannot pay, the return stays unfiled and late fee and interest continue to accrue.