IRS Direct Pay is a free, secure way to pay your federal taxes directly from a bank account at IRS.gov. You can make payments for estimated taxes, a balance due, an installment agreement, and even an offer in compromise deposit and filing fee. Payments can be scheduled up to 30 days in advance and you'll get an immediate confirmation. It's generally the safest and fastest way to pay the IRS.
If you prefer, you can also pay by debit or credit card using an IRS authorized partner, but fees will apply for those payments.