If you would like to apply for an installment agreement to pay your federal taxes over time, you may do so by phone or mail (for a fee of $225) or online (fees may apply). For taxpayers owing less than $50,000, you are encouraged to establish an installment agreement online. Applying online does not charge a fee for paying "now" or a short-term plan (paying in under 120 days). There is a fee if you are requesting a long-term payment plan (paying in more than 120 days). The setup fee for a long-term payment plan is as follows:
As such, the most inexpensive installment agreement option is to apply online and setup direct debit payments.
Visit this link to start an Online Application for an Installment Agreement
To apply by paper, you’ll need to complete Form 9465: Installment Agreement Request
If you previously registered for an Online Payment Agreement, Get Transcript, or an Identity Protection PIN (IP PIN), you should log in with the same user ID and password. You will need to confirm your identity by providing the additional information listed above if you haven’t already done so.