Rule 42 – Proportionate Reversal of ITC on Inputs and Input Services (CGST Rules, 2017)

Rule 42 of the CGST Rules, read with Section 17(1), 17(2) and 17(5) of the CGST Act, prescribes the mechanism for reversing Input Tax Credit when inputs or input services are used partly for taxable supplies and partly for exempt supplies. Since exempt supplies do not contribute GST revenue, full ITC cannot be allowed, and the rule mandates proportionate reversal based on actual usage. The rule requires monthly reversal of common ITC and an annual adjustment using actual turnover of the financial year.

1. Legislative Basis (Sections & Rules Involved)

Rule 42 derives authority primarily from Section 17 of the CGST Act, which restricts ITC relating to exempt supplies and non-business use. Section 17(5) identifies blocked ITC, Section 16 prescribes eligibility, and Section 50 mandates interest on delayed reversal. Together, these provisions guide both monthly and annual reversals, ensuring taxpayer accuracy and preventing excess ITC claim.

Legal References

• Section 16 – Eligibility & conditions for ITC.
• Section 17(1) – Restriction for non-business use.
• Section 17(2) – Restriction for exempt supplies.
• Section 17(5) – Blocked ITC.
• Rule 42 – Proportionate reversal of inputs & input services.
• Rule 43 – Reversal for capital goods.
• Section 50(1) – Interest on delayed reversal.

2. Segregation of ITC (Mandatory Categorisation Under Rule 42)

Rule 42 requires taxpayers to classify ITC into exclusive and common categories before computing reversal. Exclusive ITC relating only to taxable supplies is completely allowed, while exclusive ITC for exempt supplies or non-business purposes is fully disallowed. The portion that cannot be directly allocated becomes common ITC and must undergo the formula-driven reversal process.

Classification Required

• T1: ITC exclusively for exempt supplies (Section 17(2)).
• T2: ITC exclusively for non-business use (Section 17(1)).
• T3: ITC exclusively for taxable + zero-rated supplies (fully eligible).
• T4: ITC blocked u/s 17(5).
• C1: Common ITC = Total ITC – (T1 + T2 + T3 + T4).

3. Monthly Reversal Mechanism (Rule 42(1))

The rule mandates that common ITC (C1) must be proportionately reversed every month based on the turnover ratio of exempt to total turnover. This ensures ITC is not overstated at any stage of the year. The reversal amount is added to output tax liability via GSTR-3B under Table 4(B)(1).

Monthly Computation

• D1 = (E/F) × C1 (E = exempt turnover; F = total turnover).
• D2 = 5% of C1 (non-business portion prescribed by Rule 42).
• Total monthly reversal = D1 + D2.
• C2 = Common eligible credit = C1 – (D1 + D2).
• Reversed through GSTR-3B Table 4(B)(1).

4. Annual Adjustment (Rule 42(2))

The rule requires a year-end recalculation using actual annual turnover, ensuring mismatch between monthly and yearly reversals is corrected. If actual reversal is more than monthly reversals, the difference must be paid with interest under Section 50(1). If the annual reversal is lower, the excess reversal becomes eligible ITC and can be reclaimed.

Annual Requirements

• Compute full-year C1, D1, and D2 afresh.
• Compare with total monthly reversals already done.
• Short reversal = Make payment + interest u/s 50(1).
• Excess reversal = Claim back as ITC in September return of next FY.
• Annual working must be retained as statutory record.

5. Exempt Turnover – Items to Be Included (Explanation to Rule 42)

Exempt turnover includes supplies where GST is not payable, including nil-rated, exempt, and non-taxable supplies. Sale of land and fully completed building is also included as exempt for calculation, though it falls under Schedule III. Including all non-taxable business income ensures that proportionate reversal is precise and prevents over-claiming of ITC.

Included as Exempt Turnover

• Exempt supply under Section 2(47) & Notifications.
• Nil-rated supplies.
• Non-taxable supplies (e.g., alcohol for human consumption).
• Sale of land & sale of building after completion certificate (Schedule III).
• Outward supplies where tax is paid by recipient under RCM (supplier’s side exempt).

6. Turnover Not Treated as Exempt for Rule 42

Certain supplies are intentionally excluded from the exempt turnover definition because they are eligible for ITC or refunds. Zero-rated supplies are treated on par with taxable supplies. This prevents unnecessary reversal and ensures exporters do not lose ITC benefits.

Not Included

• Export of goods/services (Section 16, IGST Act).
• Supplies to SEZ (zero-rated).
• Supplies taxable at concessional rate.
• Interest income on loans up to Rs. 5 crore (Explanation to Section 17).
• Activities under Schedule III (except land/building sale which is specifically included).

7. Special Situations & Clarifications Under Rule 42

Rule 42 includes specific treatment rules for credit notes, abnormal turnover, negative turnover, and RCM supplies. The formula applies even if exempt turnover temporarily becomes zero. The rule also clarifies that ITC on capital goods must be handled separately under Rule 43 and cannot be mixed with Rule 42 calculations.

Key Clarifications

• Credit notes must adjust the exempt/total turnover.
• If exempt turnover is zero, entire C1 becomes eligible.
• Common ITC reversal does not apply to capital goods (Rule 43).
• Turnover includes taxable + exempt + zero-rated (but D1 only uses exempt).
• For RCM outward supplies, supplier treats turnover as exempt for Rule 42.

8. Practical Impact on Businesses

Rule 42 directly affects the monthly ITC balance, annual ITC availability, and working capital. Higher exempt turnover leads to higher reversal. The rule also necessitates strong ITC classification, document retention, and reconciliation between GSTR-2B, books, and GSTR-3B.

Business Impact

• Reduces eligible ITC when exempt turnover is high.
• Requires monthly computation and annual recomputation.
• Affects working capital if reversal amount is large.
• Demands correct classification of taxable/exempt inputs.

9. Simple Numerical Illustration (Fully Law-Compliant)

A taxpayer has both taxable and exempt turnover during a month. ITC is segregated into exclusive and common categories as per Rule 42, reversal is computed using the prescribed formula, and the balance becomes eligible ITC.

Working

• Total ITC: 1,00,000
• T3 (exclusive taxable): 40,000
• T1 (exclusive exempt): 10,000
• T4 (blocked u/s 17(5)): 5,000
• C1 = 45,000
• Exempt turnover: 10 lakh
• Total turnover: 50 lakh
• D1 = 9,000
• D2 = 2,250
• Total reversal = 11,250
• Eligible ITC = 33,750