Filing an extension for your U.S. federal tax return is generally free if you do it yourself. The IRS allows all individual filers to request an extension at no cost by using IRS Free File, paying online and selecting extension as the payment reason, or mailing Form 4868 by the April 15 deadline

. However, if you use a third-party service or tax professional to file the extension on your behalf, there may be fees involved. For example, some online services charge around $12.95 to $19.95 for filing an extension form like Form 4868 for personal returns, with additional fees for business or other types of extensions

. Tax software providers may also charge fees ranging roughly from $79 to $139 for federal filing services, though free options exist for simple returns

. In summary:

• Filing an extension yourself directly with the IRS: Free
• Using IRS Free File or paying estimated taxes online with extension option: Free
• Using third-party services or tax professionals: Typically $12.95 to $19.95 or more, depending on the service and form

Remember, an extension only gives you more time to file, not to pay any taxes owed. You must estimate and pay any balance due by the original filing deadline to avoid penalties