Inverted tax structure refunds: proportionate Net ITC allocation to inverted-rated turnover reduced by tax payable yields maximum refundable amount. Refunds under rule 89(5) are calculated by allocating Net ITC-input tax credit availed and entered into the electronic credit ledger in the relevant period-proportionally to turnover of inverted-rated supplies using Adjusted Total Turnover, and then deducting the tax payable on those inverted-rated supplies adjusted for ITC utilisation; transitional credits are excluded from Net ITC and inputs' ITC is includible irrespective of individual input rates, subject to section 17(5) restrictions.