Summary : Input tax credit is not established merely because an invoice appears in GSTR-2B. Section 16 of the CGST Act requires a registered person to satisfy the statutory conditions, while section 17 restricts credit to business use and to the portion attributable to taxable supplies, including zero-rated supplies. Section 17(5) separately blocks specified credits even where an expense has a commercial purpose. Rules 42 and 43 then prescribe attribution for common inputs, input services and capital goods used across taxable, exempt and non-business activities. A defensible file therefore needs more than a monthly portal download: it should connect each invoice to receipt, business purpose, cost centre, outward-supply profile, payment status, blocked-credit review and the correct apportionment pool. This guide presents a practical evidence map, a worked Rule 42 illustration, capital-goods controls and review questions for FY 2026-27 without treating accounting labels or system flags as conclusive legal proof.
- Four Separate Gates Decide Whether ITC Survives Review
- Business Purpose Must Be Proved at Invoice Level
- Payment Within 180 Days Is a Separate Control
- Classify Credit Before Applying the Common-Credit Formula
- Worked Rule 42 Illustration for a Mixed-Use Month
- Rule 43 Requires an Asset-by-Asset GST Register
- Section 17(5) Review Needs Facts, Not Expense Codes
- Monthly Close and Annual Evidence Pack
- Frequently Asked Questions
- Does appearance in GSTR-2B prove ITC eligibility?
- Is every expense with a business purpose eligible?
- What is common credit?
- Can one allocation key be used for every shared cost?
- How is non-business use treated under Rule 42?
- Are common capital goods handled in the same monthly pool?
- What happens when a supplier remains unpaid for 180 days?
- What should an audit file contain?
- Key Takeaways
Four Separate Gates Decide Whether ITC Survives Review
The first gate is documentary and procedural eligibility under section 16: prescribed tax document, receipt of goods or services, tax payment to Government subject to the statutory mechanism, furnishing of the return and compliance with other conditions. The second gate is purpose under section 17(1), which restricts credit to the portion used in the course or furtherance of business. The third is attribution under section 17(2), separating taxable and zero-rated use from exempt use. The fourth is the independent blocked-credit list in section 17(5). Passing one gate does not excuse failure at another.
| Gate | Question | Typical evidence |
|---|---|---|
| Section 16 | Are document, receipt, tax and return conditions met? | Invoice, GRN/service proof, GSTR-2B and return file |
| Business use | How does the cost support the enterprise? | Approval, cost centre, user record and contract |
| Taxable/exempt use | Which outward activities consume the input? | Turnover map, allocation key and management record |
| Section 17(5) | Is the credit blocked despite business purpose? | Expense-category review and statutory exception memo |
| Rules 42/43 | Is exclusive or common attribution required? | Monthly computation, asset register and annual true-up |
Business Purpose Must Be Proved at Invoice Level
A narration such as “office expense” is too weak where the same category may include personal, exempt or blocked use. The invoice file should identify the requesting department, approved business need, place and period of use, recipient GSTIN, receiving evidence and responsible cost centre. For services, deliverables, attendance, reports, system logs or correspondence may prove receipt better than a payment voucher. For goods, purchase orders, goods-receipt notes, inventory movement and installation records show where the item went.
Mixed-use expenses require a reasoned allocation method. Headcount, floor area, machine hours, transaction counts or directly measured consumption may be appropriate depending on the cost. The method should reflect actual use, be applied consistently and be approved. A convenient percentage selected after a notice is received is weaker than a contemporaneous allocation embedded in the monthly close.
Payment Within 180 Days Is a Separate Control
The payment condition attached to section 16 requires monitoring of invoice value plus tax where the recipient does not pay the supplier within the prescribed 180-day period, subject to statutory exceptions. Accounts payable and GST teams should share an ageing report that identifies unpaid invoices on which credit was availed, reversals made and later re-availment after payment. Netting, retention and disputed amounts should be analysed on the governing documents rather than mechanically marked paid.
Classify Credit Before Applying the Common-Credit Formula
Rule 42 works only after credits are sorted into meaningful pools. Inputs and input services used exclusively for non-business purposes, exclusively for exempt supplies or otherwise ineligible are excluded. Credit used exclusively for taxable supplies and zero-rated supplies is directly eligible. The residual amount is common credit, which is apportioned for exempt and non-business use under the rule. Misclassifying a directly attributable amount as common can distort the reversal in either direction.
| Pool | Treatment | Control example |
|---|---|---|
| Exclusive non-business | Exclude/reverse | Personal-use facility identified by user log |
| Exclusive exempt supply | Exclude/reverse | Consultancy tied only to exempt output |
| Blocked under section 17(5) | Exclude unless a stated exception applies | Motor vehicle or works-contract review memo |
| Exclusive taxable/zero-rated | Direct eligible credit | Input traced to taxable export service |
| Common input/input service | Apply Rule 42 attribution | Shared rent, audit or software cost |
| Common capital good | Apply Rule 43 over prescribed useful life | Server supporting taxable and exempt units |
Worked Rule 42 Illustration for a Mixed-Use Month
Assume total input and input-service credit for a month is ₹1,00,000. Of this, ₹10,000 is exclusively non-business, ₹15,000 exclusively supports exempt supplies, ₹25,000 exclusively supports taxable supplies and ₹50,000 is common credit. If exempt turnover is 20% of total turnover for the prescribed period, the exempt-use component of common credit is ₹10,000. Rule 42 also attributes 5% of common credit to non-business purposes where common inputs are used partly for non-business purposes, producing ₹2,500 in this illustration. Subject to the precise rule and facts, the remaining common amount is ₹37,500.
| Step | Amount | Meaning |
|---|---|---|
| Total credit identified | ₹1,00,000 | Starting population |
| Exclusive non-business | ₹10,000 | Not eligible |
| Exclusive exempt | ₹15,000 | Not eligible |
| Exclusive taxable | ₹25,000 | Direct eligible |
| Common credit | ₹50,000 | Subject to attribution |
| Exempt share at 20% | ₹10,000 | Common-credit reversal |
| Non-business share at 5% | ₹2,500 | Common-credit reversal |
| Remaining common credit | ₹37,500 | Eligible subject to all other conditions |
The numbers illustrate workflow, not a universal result. Turnover definitions, exclusions, State-wise registration data, special supplies and annual recalculation can change the computation. The working should cite the exact turnover source and reconcile to returns and financial records. If exact attribution is possible, direct attribution should not be abandoned merely to use a formula.
Rule 43 Requires an Asset-by-Asset GST Register
Capital goods need a separate register recording invoice, GSTIN, in-service date, location, user, taxable or exempt purpose, changes in use and disposal. Rule 43 spreads common capital-goods credit over the prescribed useful-life framework of sixty months. A later movement from exclusive taxable use to common use, or from common use to exclusive exempt use, can alter the calculation. The fixed-asset register and GST working must therefore communicate.
Depreciation policy does not replace the GST rule. Nor should tax be claimed both as ITC and included in depreciable cost contrary to the income-tax condition applicable to the entity. Finance should document the chosen accounting and tax treatment at capitalisation, retain installation evidence and update the GST status when assets are transferred, scrapped or sold.
Section 17(5) Review Needs Facts, Not Expense Codes
Blocked-credit review is frequently weakened by automated expense codes. The statutory list and exceptions turn on vehicle type and seating, onward supply, employee obligations, construction on own account, composition-tax supplies, personal consumption, lost or written-off goods and other facts. A “repairs” or “staff welfare” ledger may contain both eligible and blocked items. High-risk categories should be reviewed invoice by invoice with a brief legal conclusion and supporting facts.
A business-purpose memo cannot override an express block. Equally, the team should not reject every item in a broad ledger when a statutory exception may apply. The reviewer should identify the clause, test each element of any exception and retain evidence such as vehicle specifications, contractual obligations, outward-supply documents or plant-and-machinery analysis.
Monthly Close and Annual Evidence Pack
- Reconcile purchase register, GSTR-2B, tax documents and receipt evidence.
- Tag direct taxable, direct exempt, non-business, blocked and common credit before computation.
- Run the 180-day supplier-payment ageing and record reversals and re-availment separately.
- Calculate Rule 42 common credit with a documented turnover source and reviewer sign-off.
- Update the Rule 43 capital-goods register for additions, transfers, disposals and changes in use.
- Reconcile return disclosures, electronic credit ledger and general-ledger GST accounts.
- Preserve allocation policies, exceptions, annual recalculation and management approval.
Frequently Asked Questions
Does appearance in GSTR-2B prove ITC eligibility?
No. It supports one part of the control environment, but sections 16 and 17 and the applicable rules must also be satisfied.
Is every expense with a business purpose eligible?
No. Section 17(5) can block credit even when the expense has a commercial purpose.
What is common credit?
It is credit not exclusively attributable to taxable, exempt, non-business or otherwise ineligible use and therefore requiring apportionment.
Can one allocation key be used for every shared cost?
Not automatically. The key should reflect how the particular input or service is consumed.
How is non-business use treated under Rule 42?
For common credit used partly for non-business purposes, the rule prescribes a 5% attribution, subject to the exact facts and current text.
Are common capital goods handled in the same monthly pool?
No. Rule 43 applies a separate capital-goods method using the prescribed sixty-month framework.
What happens when a supplier remains unpaid for 180 days?
The recipient must apply the statutory reversal and later re-availment mechanism, subject to the law and exceptions.
What should an audit file contain?
It should link document, receipt, business purpose, outward use, blocked-credit review, payment ageing, computation, return and ledger evidence.
Key Takeaways
- GSTR-2B is evidence, not a complete legal entitlement test.
- Separate section 16 eligibility, business use, exempt attribution and section 17(5) blocks.
- Classify exclusive and common credits before applying Rules 42 and 43.
- Maintain a connected 180-day ageing and capital-goods register.
- Document allocation logic and annual recalculation before a dispute arises.
*****
Disclaimer: This article is a general editorial guide to input tax credit business-use evidence, sections 16 and 17 of the Central Goods and Services Tax Act, 2017, and Rules 42 and 43 of the Central Goods and Services Tax Rules, 2017, based on official material checked on 8 November 2026. It is not a legal opinion, eligibility certificate, allocation policy, audit conclusion, return-filing instruction or determination that any invoice, expense, motor vehicle, works contract, employee benefit, capital good, exempt supply, zero-rated supply or common service qualifies for credit. ITC depends on the recipient registration, tax document, actual receipt, supplier and tax-payment status, return reporting, payment terms, business purpose, place and period of use, outward-supply profile, statutory blocks and exceptions, turnover definitions, State-wise registration facts, changes in asset use and later amendments or judicial decisions. The numerical Rule 42 example is illustrative and must not be copied without recalculating the statutory variables and reviewing the current rule. Portal visibility and accounting classification do not override the Act, and the 180-day mechanism, annual adjustment and Rule 43 treatment require transaction-specific review. Taxpayers should retain contemporaneous evidence, reconcile portal and book records, and obtain advice from qualified GST and accounting professionals before availing, reversing or reclaiming credit. TaxGuru accepts no responsibility or liability for denied credit, interest, penalty, cash-flow loss, incorrect apportionment, return mismatch, audit qualification, litigation or other consequence arising from reliance on this article, incomplete records, changed facts, portal behaviour or a later change in law.
