GST CMP-08 Due 18 October 2026: Composition Tax Payment and Filing Checks

Summary: Composition taxpayers should review their July–September 2026 GST records before the ordinary 18 October 2026 deadline for Form GST CMP-08. Under Rule 62 of the Central Goods and Services Tax Rules, 2017, the quarterly statement records self-assessed liability and payment; it is separate from the annual Form GSTR-4. The statement covers outward supplies, relevant inward supplies attracting reverse charge, tax, interest and payment through the electronic cash ledger. A registered composition person cannot collect GST separately on outward supplies and generally cannot use input tax credit to discharge the composition levy. Nil activity does not by itself remove the obligation to file a nil statement where applicable. Taxpayers must verify their composition status, turnover by State or Union territory, rate category, credit and debit note adjustments, reverse-charge liabilities, and whether prior CMP-08 statements remain pending. Late payment may attract interest under section 50 even where a routine CMP-08 late-filing fee is not levied by the portal. The standard date should not be mistaken for an automatically extended deadline merely because 18 October falls on a Sunday; any specific relief requires a valid notification. This guide distinguishes filing, payment, annual reconciliation and practical controls for accountants and small businesses.

Why 18 October 2026 Matters for Composition Taxpayers

The July–September 2026 quarter ended on 30 September. Rule 62(1) ordinarily requires the registered person covered by the composition levy or the specified service-provider scheme to furnish Form GST CMP-08 by the eighteenth day of the succeeding month. That produces 18 October 2026 as the standard filing and payment date. The date is a statutory computation, not an assertion that the portal has separately issued a new October 2026 deadline announcement. Businesses should check for a subsequent class-specific or State-specific extension before finalising the compliance calendar.

CMP-08 is not the same as the monthly GSTR-3B used by regular taxpayers. It is a quarterly statement for self-assessed composition tax and relevant reverse-charge liabilities. The official form appears in the CBIC compilation of GST forms. For the broader classification of periodic forms, TaxGuru’s GST compliance guide explains the distinction between regular, QRMP and composition compliance.

Who should prepare a CMP-08 statement?

A person who has validly opted to pay tax under section 10 of the CGST Act should examine CMP-08 for every applicable quarter, including a quarter of nil business. The mechanism also covers specified registered service providers paying tax under Notification No. 02/2019-Central Tax (Rate), subject to that notification and Rule 62. A person who has shifted to the regular scheme or whose registration has changed during a quarter should first identify the precise effective date and the period for which composition reporting applies. The GSTIN-level return dashboard is more reliable than assuming that the same filing applies for the whole financial year.

Legal Framework: Section 10, Rule 62 and Form Design

Section 10 permits eligible small suppliers to pay tax at prescribed composition rates in lieu of the normal output-tax mechanism, subject to restrictions and turnover limits. It is not a blanket concession that applies to every GSTIN below a single turnover number. Supply profile, inter-State restrictions, goods or services involved, e-commerce transactions and the applicable option under the law must all be checked. Composition taxpayers issue bills of supply rather than tax invoices for their composition outward supplies, cannot separately collect the composition tax from customers and are generally ineligible for input tax credit.

Rule 62 separates the quarterly payment statement from the annual composition return. CMP-08 captures a summary of self-assessed liability; annual GSTR-4 reconciles the full year’s transactions and adjustments. The original TaxGuru CMP-08 statement-cum-challan explanation is useful for the form’s architecture, but historical late-fee or GSTR-4 dates in older commentary should not be treated as the operative 2026 position without checking amendments.

Which fields require a ledger-to-form check?

The official CMP-08 design includes GSTIN and identification fields, a liability summary and verification. In the liability table, outward supplies include exempt supplies for disclosure, while tax is computed under the applicable composition provisions. A separate line captures inward supplies attracting reverse charge, including import of services where taxable. The form then reports total tax payable, interest payable if any, and tax and interest paid. These are aggregate fields, but the accountant should maintain transaction-level working papers supporting them.

Compute Tax Only After Confirming the Correct Composition Category

A trader, manufacturer, restaurant service supplier and eligible service-provider composition taxpayer can face different conditions and prescribed effective rates. The percentage quoted for one category cannot be applied to another merely because both file CMP-08. Rates are also often expressed as the Central tax component with a corresponding State or Union territory component; comparing a one-sided rate with a combined rate can double or halve the calculation. Before approving the tax working, record the statutory category, relevant turnover definition and period, and whether any activity makes the taxpayer ineligible.

For an illustrative reconciliation, suppose an eligible taxpayer’s working shows outward turnover of ₹20,00,000 and a combined composition tax rate of 1% applicable to that taxpayer’s facts. The outward composition liability would be ₹20,000 before any relevant adjustments. This is a calculation example, not a statement that every composition supplier pays 1%. If there is separately taxable reverse-charge liability of ₹3,600, it must be evaluated on its own basis rather than automatically included in the 1% composition computation. The books should demonstrate how each component reaches the form.

Reverse charge is not absorbed into composition tax

Composition tax on outward supplies does not extinguish reverse-charge obligations on inward supplies for which the recipient is legally liable. For example, specified legal services, transport services or imported services may require a separate determination of taxability, place of supply, exemption, notification conditions and rate. The fact that a vendor’s invoice contains no GST is not enough to prove reverse charge applies, just as the absence of a tax invoice does not prove it does not apply. Keep a reverse-charge register and match each relevant transaction to its statutory charging provision.

Nil CMP-08, Payment Process and Evidence of Filing

A nil quarter still requires attention. GSTN’s official functionality note on nil CMP-08 through SMS states that eligible composition taxpayers can file a nil statement through SMS when conditions are satisfied, including the absence of outward supplies, reverse-charge liability and other tax liability. Earlier applicable statements must be filed and the authorised signatory’s mobile number must be registered. Where there is saved portal data or another disqualifying condition, the online process may be necessary.

The filing workflow should not end when a challan is generated. Cash deposited through the payment system is credited to the electronic cash ledger, whereas filing CMP-08 is a distinct authenticated action. After computing liability, verify the ledger balance, complete the relevant tax and interest payment, file using the prescribed authentication and download the acknowledgement or ARN. A screen showing “saved” or “submitted” is not the same as a filed statement. Store the final filed PDF and the payment challan in the quarter’s GST records.

Interest versus late fee: a necessary distinction

Section 50 addresses interest on tax paid after its due date. The standard notified rate for ordinary delayed tax payment has been 18% per annum, subject to the applicable statutory framework and particular facts. A simple illustration of ₹20,000 tax remaining unpaid for ten days at 18% per annum gives approximately ₹98.63: ₹20,000 × 18% × 10/365. The actual computation depends on the correct starting date, payment date and liability. Do not simply import the daily late fee applicable to GSTR-4 or GSTR-3B into CMP-08; the form is a statement-cum-challan and portal practice differs. Any separate statutory consequence must be identified independently rather than guessed.

Annual GSTR-4 Is Separate and Now Has a Different Due Date

The quarterly CMP-08 should not be confused with annual GSTR-4. The annual return for composition taxpayers generally follows the financial year, while quarterly statements settle periodic tax. The rule was amended so that the annual GSTR-4 deadline for FY 2024–25 onward is ordinarily 30 June following the year, not the historical 30 April stated in many older guides. For FY 2026–27, the standard annual date is therefore 30 June 2027, subject to later legal changes. The taxpayer should reconcile all four quarterly statements, annual turnover and reverse-charge information before annual filing.

A mid-year switch into or out of composition deserves separate treatment. The taxpayer may have regular-scheme reporting for one period and composition reporting for another. The effective date, stock-credit reversal, bills of supply, registration amendments and annual-return obligations must be reconciled instead of filing one set of forms for the entire year without checking. Also avoid assuming that filing the annual return cures an earlier delayed tax payment without interest.

Practical Pre-Filing Controls for 16–18 October

The first control is a status check: obtain the GST portal profile and confirm the active composition category for July–September 2026. The second is completeness: reconcile the sales register, cash receipts, UPI collections, credit notes, advances and turnover by GSTIN. The third is legal classification: review exempt and taxable outward supplies, reverse-charge purchases and any transaction that may invalidate composition eligibility. The fourth is calculation: confirm the combined Central and State/UT rates, adjustments and interest. The fifth is payment and evidence: confirm the electronic cash ledger, complete the filing and save the ARN.

Owners should assign responsibility for the final sign-off rather than leaving it solely to a return preparer. The person who authorises filing should review material adjustments and any assumptions about reverse charge, exempt supplies or category eligibility. Where a mismatch cannot be resolved before the deadline, document the disputed item and obtain specific professional advice; do not invent a rate or leave known liability unreported. Finally, check the live GST portal and CBIC notifications for any genuine extension or system advisory affecting the taxpayer’s GSTIN.

Frequently Asked Questions

1. What is the normal CMP-08 deadline for July–September 2026?

18 October 2026 under the quarterly Rule 62 timetable, unless a valid applicable notification extends it.

2. Does a composition taxpayer with no sales file CMP-08?

Yes, a nil CMP-08 is generally required for an applicable quarter. Nil SMS filing is available only where GSTN’s conditions are met.

3. Can a composition dealer use input tax credit to pay CMP-08?

No. The composition levy is ordinarily paid through the electronic cash ledger, and composition taxpayers generally cannot claim ITC.

4. Does a payment challan alone complete CMP-08 filing?

No. A challan funds the ledger; the authenticated CMP-08 statement must separately be filed and acknowledged.

5. Is reverse-charge tax included in the composition rate?

No. Reverse-charge liability is assessed separately under the relevant law and reflected in the applicable CMP-08 field.

6. Does delayed CMP-08 automatically attract GSTR-4 late fee?

No. CMP-08 and annual GSTR-4 have distinct legal functions. Interest on delayed tax may arise even where the portal does not impose a routine CMP-08 filing late fee.

7. When is the annual GSTR-4 for FY 2026–27 ordinarily due?

30 June 2027 under the amended annual filing rule, subject to later notification or a specific exception.

Key Takeaways

• 18 October 2026 is the ordinary Rule 62 deadline for the July–September CMP-08 statement and payment.
• Check composition eligibility, rate category, outward turnover and reverse-charge inward supplies before calculation.
• Nil quarters may require nil filing; funding the cash ledger is not equivalent to filing the statement.
• Interest on late tax payment is a separate issue from any filing late-fee treatment.
• Annual GSTR-4 and CMP-08 are different compliances; maintain a four-quarter reconciliation.

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Disclaimer: This article is published by TaxGuru for general educational and informational purposes as at 16 October 2026. It summarises the ordinary legal framework and does not constitute legal, tax, audit or professional advice for any particular taxpayer. Applicability depends on the taxpayer’s GSTIN status, State, supply profile, notifications, turnover, registration history and factual records. Dates, forms, portal features, rates and administrative practice may change through subsequent official action; readers must verify the latest CBIC and GST portal position before filing or paying. Numerical illustrations are hypothetical and do not establish any individual liability. TaxGuru accepts no responsibility or liability for errors, omissions, subsequent legal changes, reliance on this article, non-filing, penalties, interest, losses or any direct or indirect consequences arising from action or inaction based on its contents; obtain advice from a qualified professional for specific circumstances.