Provision for bad and doubtful debts must be set off against all bank bad debts before claiming write-off deduction. Actual bad debts of all branches, rural or urban, must first be set off against the provision for bad and doubtful debts already allowed under Section 36(1)(viia), which uses rural-branch advances only to quantify the permissible provision; only any excess may be claimed as a deduction under Section 36(1)(vii).