Download and print IRS Form 1040-V from the link in References below if you will be mailing a payment with a completed return or if you filed a return electronically and are now mailing a payment. Although the IRS doesn't require this form, it strongly encourages you to use it to ensure that your account is properly credited.
Fill out the payment voucher with your name, address, Social Security number and the amount of your payment.
Write a check, or obtain a money order, payable to "United States Treasury" for the amount of your payment. Write your Social Security number on the check. Also write the tax year and the type of return you are filing. So, if you were filing a Form 1040A for 2010, you would write "2010 Form 1040A."
Detach the payment voucher from the form.
Find your state on Page 2 of the form. Mail your payment and your 1040-V -- and your completed return, if applicable -- to the address that corresponds to your state. Note that there are different addresses for returns prepared by individuals and those prepared by professional tax preparers.
Download and print IRS Form 1040-ES from the link in References below if you are making an estimated tax payment for self-employment income or some other reason.
Fill out the proper coupon for the quarter of the year for which you are paying estimated taxes. Form 1040-ES comes with four coupons, one for each quarter. Include your name, address Social Security number and amount of the payment.
Write a check, or obtain a money order, payable to "United States Treasury" for the amount of your payment. Write your Social Security number on the check, along with the tax year and the ES form number, such as "2010 Form 1040-ES."
Detach the coupon from the form.
Find the section in the 1040-ES instructions titled "Where To File Your Estimated Tax Payment Voucher if Paying by Check or Money Order." Locate the proper address for your state of residence. Mail your payment and your Form 1040-ES coupon to the applicable address.
Make out a check, or obtain a money order, payable to "United States Treasury" for the amount of your payment. Write your Social Security number on the check. If you have an installment-agreement coupon or other payment voucher, follow its instructions for what else to put on the check.
Visit the link for "Other Payments" in the References section below.
Find the proper chart for your employment circumstances. One chart applies only to self-employed people who filed Schedule C or F; the other applies to people with only wage income.
Locate the proper address to send payments for your state. Mail your payment and any coupon or voucher to that address. If you have no coupon, statement or voucher, include a brief explanation of the purpose of your payment.