There is a user fee for requesting an installment agreement with the IRS using Form 9465. The fee is $120 for taxpayers whose monthly income is below a certain threshold, and $225 for taxpayers whose monthly income is above the threshold. The fee can be paid online, by mail, or by phone using a credit or debit card. Taxpayers can also pay by check or money order, but the form must be mailed to the IRS.