GST New Rules from 1 April 2026 — The Complete Guide for Indian Small Business Owners

GST New Rules April 2026 have changed how Indian small businesses file returns, claim ITC, and generate invoices, and most shop owners do not know it yet.

Suresh runs a hardware shop in Nagpur. Monthly billing around ₹8 lakh. GST registered, fairly regular with returns. Last Tuesday his CA called: "One of your main suppliers hasn't been filing on time. From April 1, your GSTR-3B might get blocked." Suresh had never heard of IMS. He had no idea what an ITC hard block was. He is not unusual. Across India, lakhs of shop owners are about to get hit by ten GST changes, and most of them do not know it yet.

Ten rules decide how a GST registered business files in FY 2026-27. Some are genuinely new from 1 April 2026. Some began earlier, in September 2025 with the 56th GST Council meeting, or in the Finance Act 2026. And a few are being reported everywhere as April 2026 changes when they have been law for two or three years already. This guide separates them, because knowing which rule started when is what tells you whether you are already non compliant or simply preparing. For small shops, kirana stores, wholesalers and MSME owners across India, that difference is the whole point.

This guide explains every change that matters. Not the corporate version, not the CA only version. The version that answers: what does this mean for my shop, and what do I need to do?

Accountune is cloud based GST billing and accounting software built for Indian small businesses, starting at ₹799 per year. It automatically handles GSTR-1 and GSTR-3B data, purchase records for IMS reconciliation, and GST rate management, so the changes below are handled in the background while you run the shop.

1. What Is Changing from GST New Rules April 2026 — Overview

Ten rules. Each one has a different impact level depending on your business type, and each one started on a different date.

2. Rule 1: ITC Hard Block — The Biggest Change of April 2026

Most guides tell you the GST portal now blocks GSTR-3B outright when your ITC does not match GSTR-2B. That is close to what is coming, but it is not accurate about today, and the difference matters if you are planning your filing process for the rest of FY 2026-27.

Three separate things are happening, on three separate timelines.

What Is Actually Locked Today

Outward liability is locked, and has been since July 2025. GSTN Advisory 606 dated 7 June 2025 made Tables 3.1 and 3.2 of GSTR-3B non editable from the July 2025 tax period. Those figures come straight from GSTR-1 and IFF. If something is wrong, the only correction route is GSTR-1A, filed before you submit GSTR-3B, and GSTR-1A can be filed only once per tax period.

Input Tax Credit in Table 4 is auto populated, but still editable. Since the October 2025 tax period, Table 4 has been filled from GSTR-2B based on the actions you take in IMS. You have still been able to adjust that figure manually before filing.

The full ITC lock is coming, not confirmed. Removing the ability to edit Table 4 is widely reported as targeted for around the July 2026 tax period. As of August 2026 there is no dated GSTN advisory confirming it is fully live. Treat it as a change to prepare for now, not as settled law, and check the portal advisory page before you plan around it.

What is not in doubt: once Table 4 is locked, a mismatch between your purchase register and GSTR-2B becomes an error you cannot fix inside GSTR-3B. The only lever will be IMS, used before GSTR-2B is generated. That is why the reconciliation habit matters now rather than later.

What causes a mismatch? Your supplier filed late. Or with errors. Or not at all. In any case, their invoices raised for you do not appear in your GSTR-2B, meaning the ITC you paid on those purchases cannot be claimed, even though you paid the GST in good faith.

Important addition from December 2025: The portal also hard blocks if RCM (Reverse Charge Mechanism) liabilities are unpaid, or if you have a negative balance in the Electronic Credit Reversal and Re-claimed Statement (ECRS). Both must be cleared before GSTR-3B opens for filing.

In short: outward liability has been locked since July 2025 and corrections go through GSTR-1A. ITC is auto populated from GSTR-2B and IMS, and the manual override is expected to go. Build the monthly habit now: check which supplier invoices have appeared in GSTR-2B before the 14th, chase the ones that have not, and file by the 20th.

What this means for you: Log into the GST portal before the 7th of each month. Check which supplier invoices appear in GSTR-2B. Follow up with any supplier who is not appearing. Accountune's purchase reports show supplier wise purchase history, giving you a clean reference list for every reconciliation.

3. Rule 2: Invoice Management System (IMS) — Your New Weekly Compliance Task

IMS launched in October 2024 and was optional. That ended on 1 April 2026, when IMS became mandatory for every regular taxpayer filing GSTR-3B. Composition dealers are outside it. This is one of the genuine April 2026 changes, and it is the one that most directly changes what you do each week.

One limit is worth knowing before you start. IMS lets you accept, reject or defer the invoices your supplier has already reported. It cannot add an invoice the supplier never reported. If a purchase is not in the system at all, no IMS action will bring it in. That is a supplier problem, not an IMS problem.

How IMS Works

Every invoice your supplier raises for you appears in your IMS dashboard on the GST portal. You choose:

• Accept: invoice is correct, goods received, ITC confirmed

• Reject: wrong amount, wrong GSTIN, goods not received

• Pending: decide later

Only accepted invoices flow into GSTR-2B as usable ITC.

New from October 2025: Bill of Entry (BoE) for imported goods, including imports from SEZ, is now also visible in IMS. If your business imports goods, you can take action on individual BoE records directly from IMS. This is a significant addition for importers and SEZ buyers.

New from February 2026: the portal added a Rejected Records tab on 18 February 2026, so invoices you rejected are now visible in one place instead of disappearing from view.

Pending invoices depend on the supplier's own filing. If they file, pending invoices get included in your GSTR-2B automatically. If they do not file, pending invoices drop out. Rejected invoices never appear, which means that ITC is permanently gone.

In short: Review IMS weekly. Accept correct invoices. Reject wrong ones promptly. Do not let the queue build. For importers, also review Bill of Entry records in IMS from the October 2025 period onwards.

What this means for you: Accountune maintains a structured purchase ledger with invoice numbers, GSTINs, amounts, and tax breakdowns. When you sit down to work through IMS on the portal, your Accountune purchase records are the reference, not scattered paper invoices or WhatsApp messages from suppliers.

4. Rule 3: GST 2.0 Rate Rationalization — Check Your Products Before 1 April

The 56th GST Council meeting in September 2025 approved the most comprehensive GST rate overhaul since 2017. Effective 22 September 2025, and fully embedded in FY 2026-27 compliance from April 2026, the messy multi slab structure is replaced by a cleaner one.

New Rate Structure — What Replaced What

Every slab, with the goods that moved and the ones that did not, is in the full slab by slab rate list.

Jewellery note: Gold, silver, and artificial or imitation jewellery remain at 3% GST under special rate provisions. HSN 7113 and HSN 7117 are both unaffected by the GST 2.0 changes.

Tobacco and cigarettes, special update: From February 2026, the GST Compensation Cess on tobacco products has been eliminated. In its place, tobacco and cigarettes are assigned new GST rates of either 18% or 40% depending on the product type, along with revamped Central Excise valuation mechanisms. Tobacco retailers and distributors must update their billing systems immediately to reflect correct rates. The old cess based calculation is no longer valid.

In short: If any product in your billing software is set at 12%, update it to 18%. If any product is at 28% and is not a luxury item, update it to 18%. Accountune users can update item rates in the item master and the change applies to all future invoices immediately.

5. Rule 4: GSTR-9 Annual Return — Do Not Ignore This

Start with the question most guides skip: does GSTR-9 apply to you at all? It does not, if your aggregate turnover is below ₹2 crore. Above ₹2 crore you file GSTR-9. Above ₹5 crore you also file GSTR-9C, the reconciliation statement. For a single kirana store, medical shop or hardware shop, GSTR-9 is often simply not required. Check your figure before you spend a day on this.

If it does apply, GSTR-9 for FY 2025-26 is due 31 December 2026.

The late fee is smaller than most guides tell you. Almost every article quotes ₹200 per day. That was the rate up to FY 2021-22. From FY 2022-23 the late fee under Section 47 is tiered by turnover:

• Turnover up to ₹5 crore: ₹50 per day, being ₹25 CGST and ₹25 SGST, capped at 0.04% of your turnover in that state or union territory

• Turnover between ₹5 crore and ₹20 crore: ₹100 per day, capped at 0.04%

• Turnover above ₹20 crore: ₹200 per day, capped at 0.5%

No late fee applies under IGST. None of this is an April 2026 change. It has been the position since FY 2022-23, and the pages telling you ₹200 per day are quoting a rate that stopped applying four years ago.

The three year bar is rolling, not a single cutoff. This is where most coverage goes wrong. Under the Finance Act 2023, brought into force on 1 October 2023 by Notification 28/2023 Central Tax, a GST return cannot be filed once three years have passed from that return's own due date. It covers returns under Sections 37, 39, 44 and 52, which means GSTR-1, GSTR-1A, GSTR-3B, GSTR-4, GSTR-5, GSTR-5A, GSTR-6, GSTR-7, GSTR-8 and GSTR-9 or 9C. The GST portal began enforcing it from the October 2025 tax period.

Rolling means each return closes on its own date. There is no single January cutoff and no blanket rule that everything from a given financial year is gone. A GSTR-3B for July 2022, due 20 August 2022, closed on 20 August 2025. The annual return for FY 2022-23, due 31 December 2023, closes on 31 December 2026, so it is still filable as this is written. Ask your CA to check each pending return against its own due date rather than writing off a whole year.

Barred does not mean forgiven. The tax liability does not expire when the filing window closes. It can still be recovered with interest and penalties, and the usual route to settle it is voluntary payment through Form DRC-03. The portal also carries an Application for Unbarring of Returns facility for cases where special approval is granted.

New from February 2026: The GST portal now auto populates the Tax Liability Breakup section in GSTR-3B for any interest or tax liability from previous periods being discharged in the current return. Taxpayers must open this tab on the payment page and click SAVE before filing, otherwise the return may not submit correctly.

In short: check whether GSTR-9 applies to you at all, because below ₹2 crore turnover it does not. If it does, FY 2025-26 is due 31 December 2026, and for a business under ₹5 crore the late fee is ₹50 per day capped at 0.04% of state turnover. Have your CA check each pending old return against its own due date. And always click SAVE in the Tax Liability Breakup tab before submitting GSTR-3B.

6. Rule 5: Post-Sale Discounts — Simpler But With New ITC Obligation

Earlier, a post sale discount, whether a volume discount, festival offer or year end rebate, was only deductible from taxable GST value if there was a written agreement before the supply. Budget 2026 removed this prior agreement requirement under Section 15.

However, there is a new obligation on the buyer side. Section 34 is now explicitly amended: when a supplier issues a credit note to reduce their tax liability, the recipient must reverse the corresponding ITC they had already claimed. This reversal must happen through IMS on the GST portal. If the recipient has not claimed ITC on the relevant invoice, no reversal is needed.

What this means in practice: Issuing a credit note is now simpler for the supplier, with no prior agreement needed. But both supplier and buyer must ensure the ITC reversal happens correctly through IMS. Missed reversals on the buyer's side can trigger compliance notices.

In short: Post sale discounts from April 2026 need no prior written agreement. Issue the credit note. The buyer reverses ITC through IMS. Both parties must coordinate. Accountune handles credit notes within the billing workflow, linked to the original invoice with GST adjustment auto calculated.

7. Rule 6: Export Refunds — No More Minimum Threshold

If your business exports goods or sells to SEZ units with payment of IGST, you were entitled to a refund, but only if the amount exceeded ₹1,000 under Section 54(14). That mattered most to small exporters shipping by courier or post, where a single consignment is often worth less than the threshold.

From 1 April 2026, the ₹1,000 minimum threshold is removed. Any amount of IGST paid on exports is refundable. Additionally, inverted duty structure refunds now qualify for provisional refunds during final processing, improving cash flow while the full refund works through the system.

Provisional refunds were introduced to cut the working capital that sits blocked while a claim is verified. If you export regularly, ask your CA what provisional refund percentage and timeline currently apply to your risk category, because that is administered case by case rather than by a single published rule.

In short: File refund claims for all IGST paid on exports. No amount is too small now. Accountune's GST summary report shows IGST paid per transaction, making refund documentation clean and ready.

8. Rule 7: Intermediary Services — Zero GST for IT and Service Exporters

This is the single biggest relief in the 2026 changes for service businesses. Previously, Indian companies providing services to overseas clients, including IT firms, back office operators, marketing agencies and consulting firms, were taxed at 18% GST even though the client was outside India.

The Finance Act 2026 received Presidential assent on 30 March 2026 and omitted clause (b) of Section 13(8) of the IGST Act with effect from that same date. Note the date: 30 March, not 1 April. Services rendered on or after 30 March 2026 are governed by the amended law regardless of when the invoice was raised or payment received.

With that clause gone, the place of supply falls back to the default rule in Section 13(2), which is the location of the recipient. If your client is in the US, UK, UAE or anywhere outside India, and you are paid in convertible foreign exchange, the service can qualify as an export of service. Zero GST, and ITC on the inputs used to deliver it.

Two cautions before you act on this. The definition of intermediary under Section 2(13) has not changed, and CBIC Circular 159/15/2021-GST still applies, so confirm you actually qualify as an intermediary before assuming zero rating. And if you received an advance before 30 March 2026 for services delivered later, the portion where the time of supply was triggered before that date still sits under the old rule.

LUT reminder: To export services without paying GST, you must submit a Letter of Undertaking (LUT) for FY 2026-27. This should have been submitted by 31 March 2026. If not done yet, submit immediately. You cannot claim zero rated status without a valid LUT for the current financial year.

The same change creates a new liability for buyers. If your business pays a foreign agent or commission facilitator to arrange deals abroad, the place of supply for that service is now India, because you are the recipient. That makes it an import of service. You must pay IGST under the reverse charge mechanism, raise a self invoice under Section 31(3)(f) of the CGST Act, and report it in your returns. ITC on that RCM payment is available where the underlying supply is for a taxable purpose, so the transaction is usually tax neutral, but the compliance step is not optional.

Businesses that paid 18% GST on intermediary services in prior years should discuss retrospective refund eligibility with their CA.

In short: IT companies, consultants and agencies serving overseas clients pay zero GST from 30 March 2026. Submit LUT immediately if not done. If you pay foreign agents, set up the reverse charge process. Talk to your CA about retrospective refunds for prior periods.

9. Rule 8: Bank Account Validation — Easy to Miss, Very High Impact

This is the most overlooked rule on the list. If a GST registered business has not furnished valid bank account details on the portal, the registration can be suspended. The action itself takes five minutes and the downside of ignoring it is out of all proportion to the effort.

A suspended registration means:

• You cannot file GST returns

• You cannot generate E-Way Bills

• Your buyers cannot claim ITC on your invoices

• You cannot generate e-invoices

How to check: Log into the GST portal, go to My Profile, then Bank Account Details. Verify that at least one active bank account with correct IFSC and account number is on record.

In short: Take 5 minutes right now. Log into the GST portal. Check that your bank account details are current and verified. This single task can prevent your entire GST registration from getting suspended.

10. Rule 9: E-Invoicing ₹5 Crore Threshold — Newly Covered Businesses

This is the rule most often reported wrongly as an April 2026 change. It is not. The ₹5 crore e-invoicing threshold came into force on 1 August 2023 under Notification 10/2023 Central Tax and has not moved since. It applies to any business whose Aggregate Annual Turnover crossed ₹5 crore in any financial year from FY 2017-18 onwards, not just the current one.

What is genuinely new for FY 2026-27 is narrower: a business that crossed ₹5 crore for the first time in FY 2025-26 becomes covered from 1 April 2026 and must be registered on the IRP before raising its first qualifying invoice. If you were already above the threshold, nothing changed for you on 1 April.

This is the rule that catches most businesses off guard. If your turnover crossed ₹5 crore even once in any past year, e-invoicing applies to you right now, even if your current year turnover is lower.

This means:

• Every B2B invoice must be uploaded to the Invoice Registration Portal (IRP)

• IRP assigns a unique IRN (Invoice Reference Number)

• IRN and QR code must appear on the printed invoice

• Buyers cannot claim ITC on a B2B invoice without a valid IRN

• If your business has GSTINs in multiple states, combined turnover of all GSTINs determines applicability

Some sectors stay exempt even above ₹5 crore, including banks, NBFCs, insurers, goods transport agencies, passenger transport operators and multiplex cinemas. E-invoicing also covers B2B invoices, exports and SEZ supplies, not B2C retail sales.

If you are not yet generating e-invoices and your turnover has ever crossed ₹5 crore, set it up immediately. Invoices issued without IRN are legally invalid for ITC purposes.

Accountune generates the IRN inside the billing flow. Create the B2B invoice and the IRN comes back automatically, with no separate portal login and no JSON upload. Current plan details are on the pricing page.

In short: the threshold is ₹5 crore and has been since August 2023. Check whether your turnover crossed it in any year from FY 2017-18 onwards. If it did, e-invoicing applies to you now. If FY 2025-26 was the first year you crossed it, you are covered from 1 April 2026.

11. Rule 10: 30-Day IRN Upload Rule — For ₹10 Crore+ Businesses

For businesses with AATO of ₹10 crore and above, a 30 day window applies for uploading invoices to the IRP. This came in on 1 April 2025, so it is a year old, not an April 2026 change. It is on this list because businesses newly crossing ₹10 crore keep discovering it late.

If an invoice is not uploaded within 30 days of the invoice date, the IRP permanently blocks IRN generation for that invoice. This applies to invoices, credit notes and debit notes. After the 30 day window closes there is no workaround. The invoice cannot get an IRN, and the buyer loses ITC on it.

Practical impact: high volume businesses whose staff process invoices in batches need same day or next day IRN generation as a standard process. Stacking invoices for end of month processing is not safe above ₹10 crore AATO.

In short: Above ₹10 crore AATO, generate IRN on every B2B invoice within 30 days of the invoice date. Build this into your daily billing process. Accountune generates IRN at the moment of invoice creation, with no batch processing delay.

12. How Accountune Handles All 10 Changes Automatically

Most small business owners are not going to manually reconcile IMS every week, verify supplier filings before claiming ITC, update product rates across hundreds of SKUs, and track IRN deadlines. That is exactly what billing software exists to handle.

ITC Hard Block, clean purchase records ready. Accountune records every purchase against a specific supplier with invoice number, GSTIN, amount, and GST breakdown. Your supplier wise purchase report is the exact reference needed to check against GSTR-2B before filing GSTR-3B.

IMS reconciliation, organised data. When you log into the GST portal to accept or reject invoices in IMS, your Accountune purchase ledger is the reference. Every invoice is recorded with date, supplier name, GSTIN, and tax amount, matching exactly what appears in IMS.

GST rate updates, bulk item master update. Update any product rate in Accountune's item master once and it applies to all future invoices immediately. No item by item updates at the counter. No risk of billing at the wrong rate.

GSTR-1 and GSTR-3B, auto generated every month. Every bill you create in Accountune feeds into GSTR-1 and GSTR-3B data automatically. At month end, your CA downloads the ready format data. No manual compilation. No calls asking you to send data at 10 PM on the 10th of the month.

E-Invoicing, IRN generated at billing. Accountune generates the IRN at the moment you create a B2B invoice. No separate portal login, no JSON upload, no 30 day deadline to chase. QR code and IRN print on the invoice automatically.

Credit notes, within the billing flow. Post sale discount? Issue a credit note in Accountune, link it to the original invoice, and the GST adjustment is calculated and reflected in reports automatically. Your CA can verify the ITC reversal obligation from the same report.

Tally is sold as a one time licence plus an annual maintenance subscription, and it expects someone in the shop to understand accounting. Accountune starts at ₹799 a year and expects no accounting knowledge. Vyapar sells desktop access on a separate plan and has no CA remote login. Accountune runs on web, Android and iOS, and a CA can log in remotely.

13. Accountune vs Vyapar vs Tally: GST Compliance Compared

14. Eight Point Checklist for FY 2026-27

Print this. Tick each one off.

1. Open your billing software item master. Find every product set at 12% GST and update to 18%. Find products at 28% that are not luxury goods and update to 18%. Save all changes before you raise your next invoice.

2. Log into the GST portal. Go to IMS. Review the queue. Accept every correct supplier invoice. Reject any invoice with wrong amounts, wrong GSTIN, or goods you did not receive. If you import goods, also review Bill of Entry records. Do not leave the queue untouched.

3. Check your bank account details on the GST portal right now. Go to My Profile, then Bank Account Details. If outdated or missing, update immediately to prevent suspension of your GST registration. Also verify that Aadhaar authentication is completed on your profile. It is now mandatory for filing refund claims (RFD-01) and for revocation of cancelled GST registration. Without it, refund applications will be rejected by the portal.

4. Confirm that Multi-Factor Authentication (MFA) is active on your GST portal account. MFA is mandatory for all taxpayers. Without MFA, you may face session failures when generating e-invoices or e-way bills during peak filing periods.

5. Ask your CA three things. Was your aggregate turnover above ₹2 crore, which is what makes GSTR-9 applicable at all? Is GSTR-9 for FY 2024-25 filed? Are any older returns close to their own three year cut off, checked return by return rather than year by year? Also confirm LUT is submitted for FY 2026-27 if you export services.

6. Make a list of your top 10 suppliers. Check if each one has been filing returns regularly. Any supplier who is consistently late will block your ITC. Have a direct conversation or plan to stop claiming ITC from that supplier until they comply.

7. Check if your turnover has ever crossed ₹5 crore in any year since FY 2017-18. If yes, e-invoicing is mandatory for you right now, regardless of current year turnover. If above ₹10 crore, implement same day IRN generation as a daily process.

8. If your business exports goods or services to clients outside India, call your CA today. You may qualify for zero GST on services and ITC on all inputs. You may also have a retrospective refund claim for GST paid on overseas client services in earlier years. And if you pay foreign agents, you now have a new reverse charge obligation to set up.