The due date for deduction is either at the time of giving credit or payment of the dues, whichever is earlier. Late deduction happens in the event the tax is not deducted when the deduction is due and is deducted at a later date. The interest for the delay in deduction is charged at the rate of 1% per month or part of a month of the delay. For Example if the due date for a deduction is 2nd of June and it is deducted on 8th of July in the same year, then the interest is charged at the rate of 1% for each month i.e. (June & July) aggregating to 2% interest.
Important: there is a difference between late deduction and late payment. Learn more
Interest on Late Payment of TDS