GST Monthly Filing Calendar May 2026: GSTR-1 by 11th, GSTR-3B by 20th, and the Late-Fee Trigger

By 23:59 IST on 11 May 2026, every regular GST monthly filer must upload GSTR-1, the outward-supplies return that feeds the buyer's input-tax-credit (ITC) ledger. Skip it, and the customer's ITC goes into limbo. That single date is the spine of the May 2026 GST calendar, followed by three more compliance cliffs before month-end.

For treasurers tracking working capital, the GST calendar is also a market signal. Every GSTR-3B cycle pulls cash out of corporate accounts in a 20-day rhythm, and the monthly GST collection number, released on the 1st of the following month by the Press Information Bureau, has become a coincident indicator that moves bond yields and PSU bank stocks. Below is the full May 2026 watchlist, with citations, tables, and late-fee maths.

Statutory Deadlines

May 2026 is a 31-day month with no public-holiday extension on GST filings. The Central Board of Indirect Taxes and Customs (CBIC) calendar on gst.gov.in lists six discrete return-types relevant to most filers, plus the QRMP track for those under the Rs 5 crore turnover threshold.

Table 1 — GST May 2026 deadlines

The QRMP split mirrors the state buckets used since the scheme launched in January 2021. Category A (22nd) covers the southern and western belt: Maharashtra, Karnataka, Goa, Gujarat, Madhya Pradesh, Chhattisgarh, Telangana, Andhra Pradesh, Tamil Nadu, Kerala, plus Puducherry, Andaman and Nicobar, Lakshadweep, Daman and Diu, and Dadra and Nagar Haveli. Category B (24th) covers the northern, eastern, and north-eastern states.

For filers who miss the 20 May 2026 GSTR-3B cut-off, the CGST Act lays out two distinct charges that compound:

• Late fee under Section 47: Rs 50 per day (Rs 25 CGST plus Rs 25 SGST) for returns with tax liability, capped at Rs 5,000 per Act per return. For nil returns the fee drops to Rs 20 per day (Rs 10 CGST plus Rs 10 SGST). For taxpayers with annual turnover up to Rs 1.5 crore the cap is Rs 2,000; for turnover Rs 1.5 to 5 crore the cap is Rs 5,000 (Notification 19/2021-CT, 1 June 2021).
• Interest under Section 50: 18 per cent per annum on the net tax liability paid through the electronic cash ledger. Interest runs from the day after the due date until the actual payment date.

A 30-day delay on a Rs 4 lakh tax liability therefore costs Rs 1,500 in late fee plus roughly Rs 5,918 in interest, a Rs 7,418 hit, before any consequential ITC blockage on the buyer side.

Beyond GST, three other statutory anchors fall in the same window. TDS for April 2026 deductions must be deposited by 7 May 2026 under Rule 30 of the Income-tax Rules. Provident-fund contributions for April are due by 15 May 2026 under para 38 of the EPF Scheme 1952 (see epfindia.gov.in). Employees' State Insurance contributions are due by 15 May 2026 under Reg 31 of the ESI Regulations. Stack these together and the third week of May becomes a multi-statute payroll cliff for any entity with employees on rolls.

Market Events

The macro-data point most directly tied to the May 2026 GST calendar is the headline collection number. Since June 2017, the Ministry of Finance has released aggregate GST collections on the first working day of each month. The May 2026 collection figure (covering April 2026 transactions) will hit the wires around 1 June 2026, and bond markets typically read it within minutes. A print above Rs 1.85 lakh crore tends to firm 10-year G-sec yields by 1 to 3 basis points on the day, while a sub-Rs 1.7 lakh crore print weakens them by a similar margin, based on the pattern observed in monthly releases through FY 2024-25 and FY 2025-26.

For equity investors, the GST cycle has indirect effects on PSU banking liquidity. CGST and SGST payments route through authorised banks under RBI's agency-banking framework on rbi.org.in, which generates short-dated float income. The 20 May 2026 settlement date is also when most large MSME working-capital lines are drawn down to fund the tax payment, marginally tightening overnight money-market rates between 19 and 21 May.

There are no scheduled RBI monetary policy committee meetings in May 2026; the next MPC after the April review concludes its cycle in June, as detailed in our RBI June 2026 pre-MPC preview. This means the GST collection number on 1 June 2026 lands without competing macro noise and could move yields on its own.

Earnings

Q4 FY 2025-26 (January to March 2026) results disclosure runs through this window. SEBI's Listing Obligations and Disclosure Requirements (LODR) Regulations 2015, Regulation 33(3)(d), require listed entities to submit standalone and consolidated audited financial results for the year-ended quarter within 60 days of quarter-end. For 31 March 2026 books that means a hard deadline of 30 May 2026, and the bulk of large-cap prints therefore cluster between the second week of May and the very last week of the month.

The briefing notes for this watchlist do not flag specific company results, and Oquilia's editorial policy is to publish only confirmed earnings dates. Investors tracking individual names should pull the company-issued board-meeting intimations filed under LODR Reg 29(2), which require 5 working days' notice for board meetings considering financial results. These intimations are searchable on the BSE and NSE corporate-announcement feeds linked from each exchange's homepage at sebi.gov.in.

For sectoral allocators, two structural reads from earlier prints carry through into the May 2026 reporting season: the GST input-credit ratio reported in the cost-of-goods-sold workings of FMCG companies, and the deferred-tax-liability swings that follow tax-rate changes notified during the year. Both link back to the F&O segment margin rules SEBI 2024 update we covered earlier, where higher upfront margins compressed positioning ahead of result-day moves.

Practical Takeaways

The actionable shortlist for the May 2026 GST window:

1. Lock the 11 May GSTR-1 filing two working days early. Most ITC-mismatch notices issued under Section 73 of the CGST Act trace back to last-minute uploads where invoice-level errors went uncaught.
2. Reconcile GSTR-2B (auto-populated on the 14th of every month under Rule 60) before drafting GSTR-3B for the 20th. The November 2024 amendment to Rule 36(4) means provisional ITC is no longer permitted; only invoices reflected in GSTR-2B are admissible.
3. For QRMP filers, the 13 May 2026 IFF upload is optional but commercially decisive. Buyers' GSTR-2B for May 2026 can include only those B2B invoices uploaded via IFF before the 14th.
4. Use the SIP calculator and lumpsum calculator to model the after-tax surplus released by efficient GST cash-flow planning. Every Rs 7,000 saved in late-fee-plus-interest, redirected at a 12 per cent SIP CAGR, compounds to roughly Rs 21,700 over 10 years.
5. Cross-check the 31 July 2026 income-tax filing trail against the GST turnover declared this May. The GST-IT reconciliation flag has been the single largest scrutiny trigger in FY 2025-26, as discussed in our income-tax due-date primer.

Table 2 — Late-fee plus interest illustration on a Rs 4 lakh GSTR-3B liability

You can model your own scenario on the step-up SIP calculator, but the simpler takeaway is that the 18 per cent interest leg is uncapped, so delays compound long after the Rs 5,000 fee ceiling is reached.

FAQ

What happens if I file GSTR-3B for May 2026 one day late?

A one-day delay attracts Rs 50 (Rs 25 CGST plus Rs 25 SGST) under Section 47 of the CGST Act for a return with tax liability, and Rs 20 for a nil return. Interest at 18 per cent per annum under Section 50 also runs for that one day on the net cash component of the tax. For a Rs 1 lakh liability the interest is roughly Rs 49, modest in isolation, but it triggers GSTN's auto-flag on your dashboard, which compliance-rating systems read.

Can I file GSTR-1 after the 11th if I have not yet collected payment from my customer?

Yes. GSTR-1 reports outward supplies, not collections. The CGST Act, Section 12, fixes time of supply at the earlier of the invoice date, payment-receipt date, or the statutory due date for invoice issue. Late filing of GSTR-1 attracts Rs 50 per day (Rs 20 for nil) under Section 47 and blocks subsequent GSTR-1 uploads under Rule 59(6) once you cross two consecutive default cycles.

Is the QRMP scheme worth opting into for FY 2026-27?

QRMP suits filers with stable monthly turnover under Rs 5 crore who can pay tax in fixed quarterly tranches. It does not reduce your tax liability; the tax payment is still monthly through the PMT-06 challan, but it cuts return-filing frequency from 12 GSTR-3B filings a year to 4. The trade-off is that buyers see your B2B invoices monthly only if you upload via IFF; otherwise they wait until the quarterly GSTR-1.

Does the 18 per cent interest under Section 50 apply to the entire tax or only the cash leg?

Only the net cash leg. The Finance Act 2021 amendment (effective 1 July 2017 retrospectively) confirmed via the Section 50(1) proviso that interest on delayed GSTR-3B applies only to that portion of the output tax paid through the electronic cash ledger, not the part settled via the electronic credit ledger (ITC). This was clarified by CBIC Circular 192/04/2023-GST.

What is the late-fee cap for a small business with Rs 80 lakh turnover?

Under Notification 19/2021-CT dated 1 June 2021, taxpayers with annual aggregate turnover up to Rs 1.5 crore face a maximum late fee of Rs 2,000 per return (Rs 1,000 CGST plus Rs 1,000 SGST). The Rs 5,000 cap applies to the Rs 1.5 to 5 crore bracket. For nil returns across all turnover bands, the cap is Rs 500 per return.

Will the May 2026 GST collection number affect bond yields?

Indirectly. The headline number released on or around 1 June 2026 by the Ministry of Finance is read as a proxy for nominal GDP growth and tax buoyancy. A higher print signals stronger fiscal receipts, which can compress the borrowing programme and pull G-sec yields lower. Markets typically react within the first 30 minutes of the release, and bond traders then cross-reference the print with the RBI's borrowing calendar published on rbi.org.in.

How do I claim a refund if I overpaid GST in May 2026?

File Form GST RFD-01 within two years of the relevant date under Section 54 of the CGST Act. The relevant date for excess cash-ledger balances is the date of payment. Refunds are processed within 60 days of acknowledgement under Section 56; if delayed beyond that, the government pays interest at 6 per cent per annum on the refund amount.