If you did not specify a date to take the funds from your account the default date is April 18th. The IRS may not even deduct the funds then because of them being so busy this time of year. It is OK, as long as you have filed and entered your payment information by or before the filing date (April 18, 2016) there is no penalty or interest.
To verify the date that Federal funds will be withdrawn from
your account, confirm that funds have been transferred, or cancel the
transaction up to 48 hours before the date you designated the funds to be
debited, call the IRS at 1 (888) 353-4537.
https://ttlc.intuit.com/replies/3300043
