Deductibility of partner remuneration: subject to working partner status, deed authorisation, non retroactivity and book profit limits. Section 40(b) permits deduction for interest, bonus, commission or remuneration paid by a firm to a working partner only if the partnership deed specifies amounts or a method of quantification, payments relate to periods after the deed's date, and interest does not exceed the authorised rate; payments to non-working partners are disallowed. Interest on fixed capital is deductible when expressly authorised; interest on current capital and loan accounts is not deductible unless specifically authorised. Book profit computation for permissible remuneration excludes brought forward losses and Chapter VI-A deductions, deducts depreciation, and adds back remuneration charged to profit and loss.