What are estimated tax vouchers?

An estimated tax voucher is a portion of form 1040 ES, which is an information packet and series of forms used to calculate and pay estimated quarterly tax payments, according to the IRS. The vouchers themselves are a series of four mailing slips that are sent with the payments.

Estimated tax payments are typically made by self-employed taxpayers, or taxpayers who don't have their taxes initially withheld from their paychecks, according to Forbes. While form 1040 ES can be used to pay estimated taxes, the Electronic Federal Tax Payment System allows taxpayers to handle their estimated taxes without having to mail physical forms.