Assuming you are referring to a 2018 tax return and you have taxes owed. You do not have to pay the 2018 taxes owed when you file the 2018 tax return. Just select to pay with a check by mail with a payment voucher, e-file your tax return and not pay by mail.
Since any taxes owed were due and payable on April 15, 2019 you are accruing penalties and interest on the unpaid taxes.
You can pay the taxes owed at any time using this IRS website - https://www.irs.gov/payments
To request a payment plan after the tax return is filed, go to this IRS website - https://www.irs.gov/payments/online-payment-agreement-application
