Originally Posted by DJMeatBall
The most basic question of all: When I do make my payment, what do I send in along with my estimated tax voucher and my 1040 returns? A printout of the payment or some confirmation e-mail or?
If you e-file, you send no credit card information. If you paper file and pay before mailing your return, you can write your confirmation number in the upper left-hand corner of the first page of your 1040. If you paper file and pay after mailing the return, you don't have to send anything. Do not send Form 1040V either.
Sometime after April 17 the IRS will match your Social Security number with the credit card payments to verify that your balance was paid on time. Keep your confirmation number in case the IRS ever says you didn't pay on time.