I have a penalty for underpayment of Estimated Tax of $8. i cant find a voucher to send my payment. is there documents that i need to send with my payment?

[Opus 17]

The payment would be added to your tax bill or subtracted from your refund automatically, there is no separate voucher.

But, for that small amount, I would go back and review the penalty again only click "Skip" and don't let Turbotax add it to your return.   Tax prep software estimates of penalties can be high or low because the IRS figures them differently. Let the IRS bill you if they really want to for that small amount. 

[jeniffer-ardon]

Cool Thanks