It depends. If your payment with extension plus any withholding and credits on your tax return cover your tax liability then there will not be any further payments due nor any penalties/interest due. If, however, you still have a tax liability after all payments were applied by 15 Apr then interest and penalties for failure to pay will have accrued since 15 Apr and will be due with your filing.
Finally, if after all payments by 15 Apr are applied and if they exceed your tax liability, the overpayment will be refunded.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
