Finance charges definition clarifies deductible interest, specified exclusions, and payment-or-accrual rule for interest to financial institutions. Defines finance charges as interest on borrowed capital or debt, interest to trade creditors, participant payments under unincorporated body formation agreements (within prescribed limits), incidental financial charges, and proportionate bond or debenture discount or premium. Excludes interest on borrowings for capital asset acquisition before commencement or first use, incidental charges on issuing convertible securities or share capital, and certain MSME Act interest. Interest payable to financial institutions is deductible in the later of payment or accrual years, while converted interest is not deemed paid; capital borrowed includes periodic subscriptions to qualifying mutual benefit finance companies.