Learn the IRS table behind your result and the page each figure was read from.
One small table of IRS user fees and rules, copied from this section's payment plan and offer guides with the page each figure was read from: the IRS payment plans page and its Simple Payment Plans page for the setup fees and the online lines, the quarterly interest rate page, the failure-to-pay penalty page, the offer in compromise page, the Form 656-B booklet with its income table, and two sections of the Internal Revenue Code, 26 U.S.C. 6159 for the low-income user fee and 26 U.S.C. 7122 for the 20 percent lump-sum payment. Every figure was read on October 14, 2026.
Nothing in a result is a figure this estimator works out for itself. The setup fee, the application fee, the first payment rule, the online lines, the interest rate and the penalty rates are printed as the IRS states them. The only comparison it makes is between the balance you type into the form and the two dollar lines the IRS sets for online requests.