Hi,
Please don't get confused. The due date for the month of March upto 30th March is 7th April. The due date for TDS deducted on 31st March only is 31st May. You have to deduct TDS and deposit accordingly. But if you are late in deduction and deposit, then you can deposit the TDS of full March month by due date of filing of ITR. In that case the expense shall not be disallowed. If it deposited after that date, the the relevant expenses shall be disallowed in relevant previous year, and shall be allowed in the previous year in which such late TDS is deposited.
And last date of filing etds return for March quarter is June 15th.
Hope I have clarified the doubts...
Thanks
Arnav