Interest for delayed income-tax returns: simple monthly interest applies, reduced by advance tax and tax credits. Interest is payable where a return is furnished after the due date or not furnished; simple interest accrues monthly from the day after the due date until furnishing or assessment completion on the tax on total income as determined under assessment, reduced by advance tax, tax deducted or collected at source and specified reliefs or credits. Separate late-return interest applies where a return required by notice is tardy, computed on the excess tax from reassessment, and any change in tax by subsequent orders increases or reduces interest with corresponding notice or refund mechanisms.