The most-repeated answer to this question on the internet — “your balance divided by 72, with a $25 minimum” — describes rules that no longer exist. The 72-month framework was abolished when the Simple Payment Plan replaced streamlined agreements, and a flat $25 minimum payment appears nowhere in the current Internal Revenue Manual; it survives in older guides and practitioner literature, not in IRM 5.14. What actually floors your monthly payment in 2026 depends on which of three lanes your balance puts you in. This page derives the number in each lane, with worked figures — what a plan costs at a given payment is the fees and interest page’s job; this page owns how the floor itself is set.
General information, not tax or legal advice. Worked examples state their assumptions in line and use the Q4 2026 interest rate (7%); the IRS computes your actual minimum with its own calculator against your actual collection statute date.
The rule: your payment must full-pay the balance — including projected penalties and interest — by your Collection Statute Expiration Date (CSED), the 10-year collection deadline. The IRS computes the figure with its payment calculator (IRM 5.14.5.2). There is no ability-to-pay test in this lane, no financial statement, and no negotiation over the number: it is arithmetic, driven by two inputs — your balance and how much of the 10 years is left.
Worked example, assumptions stated: a $30,000 assessed balance, interest at 7%, failure-to-pay at the in-plan 0.25% rate.
Same debt, two different minimums — the CSED, not a divisor, is doing the work. Two consequences follow. First, waiting hurts twice: the balance grows while the runway shrinks. Second, you may pay the balance down to $50,000 before an agreement is granted to enter this lane — but you cannot use the first installment payment itself to get under the line.
The statutory lane (IRC §6159(c)): if you meet the conditions — income tax only of $10,000 or less (penalties and interest don’t count against the cap), no failure to file or pay and no installment agreement in the preceding five tax years — the IRS must accept the agreement. The floor here is set by the 3-year rule: full payment within 3 years or by the CSED, whichever is earlier.
On a $10,000 tax bill that floors at roughly $310–$325 a month once penalties and interest are in the balance. If you cannot reach that number, you are not refused help — you simply aren’t in the guaranteed lane. Lane 1’s longer runway (or Lane 3’s analysis) is where the application goes next, and the IRM directs employees to consider a Simple Payment Plan for anyone who misses guaranteed criteria.
Here the “minimum” is not a formula at all. It is your monthly disposable income (MDI) from a Form 433 financial analysis: income minus allowable living expenses, measured against the IRS Collection Financial Standards — your actual spending counts only up to the standard amounts. The IRS generally expects the full MDI as the payment.
One place ÷72 genuinely survives: the paper form’s blank-line default. The Form 9465 instructions say that if you list no payment amount, the IRS will determine one “by dividing the balance due by 72 months.” Treat that as a trap, not a minimum: a blank line proposes a 72-month payoff whether or not it fits your budget or your CSED, and under current rules what the IRS will accept is governed by Lane 1’s full-pay-by-CSED test, not by the divisor. Always write a number on the form — the line-by-line consequences are in the Form 9465 walkthrough.
Run it through the lanes. On a $10,000 balance with a long statute runway, Lane 1’s math can land near $100–$120 — plausible. On a $40,000 balance with five years left, $100 doesn’t retire a fifth of the balance before the CSED, so the online tool will prompt you to revise upward, and insisting on $100 routes you to Form 433 analysis — where $100 is accepted only if it equals your documented disposable income, in which case the product is a partial payment agreement, not a discount. Below-floor proposals are never “rejected and forgotten”; they change lanes.
Two interactions that surprise people:
If your sustainable number is below every lane’s floor, the honest next comparisons are a partial payment agreement (Lane 3’s endpoint) and the non-plan alternatives routed from the payment plans hub — not a lower offer into the online tool.
What is the minimum monthly payment for an IRS installment plan? There is no single figure and no flat dollar floor in the current manual. Under a Simple Payment Plan ($50,000 or less assessed) the minimum is the payment that full-pays your balance, including projected accruals, by your 10-year collection statute date — computed by the IRS, and lower the more of the statute remains. A guaranteed agreement ($10,000 tax or less) floors at full pay within 3 years. Above $50,000, the minimum is your documented monthly disposable income from a Form 433 analysis.
Will the IRS accept $100 a month? Only if the math puts your floor there: roughly, a small balance with a long statute runway under the Simple Payment Plan, or $100 as your documented disposable income in a Form 433 analysis (which produces a partial payment agreement). On a mid-five-figure balance with a few years of statute left, $100 cannot full-pay by the deadline and will not be accepted as proposed.
How is my monthly payment amount determined if I don’t propose one? On paper, by the form’s fallback: file Form 9465 with the payment line blank and the IRS divides the balance due by 72 months. Online, the tool computes the full-pay-by-CSED amount for you. Neither default knows your budget — proposing your own sustainable number, at or above the floor for your lane, is always the better move.
General tax information, not tax or legal advice. Sources: IRM 5.14.5.2 (Simple Payment Plan full-pay-by-CSED rule; IAT calculator; pay-down-to-qualify); IRM 5.14.5.3 and IRC §6159(c) (guaranteed agreements); IRM 5.14.2 / 5.15.1 (Form 433 disposable income, Collection Financial Standards); Instructions for Form 9465 (Rev. July 2024) (divide-by-72 default — the $25 figure cited in older guides does not appear in IRM 5.14.1/5.14.5 as of the July 2026 revisions). Currency verified 2026-10-23.