Yes, the IRS does charge interest on payment plans, and setting one up does not pause or reduce it. Interest runs on your unpaid balance at 7% for the first quarter of 2026, compounded daily, from the original return due date until you pay in full.1Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 The one break a payment plan gives you is on the failure-to-pay penalty, which drops from 0.5% to 0.25% per month once your installment agreement is approved, as long as you filed your return on time.2Office of the Law Revision Counsel. 26 U.S. Code 6651 – Failure to File Tax Return or to Pay Tax
How the Interest Rate Works
The IRS sets its underpayment rate each quarter based on the federal short-term rate plus three percentage points. For the first quarter of 2026, that rate is 7%.1Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 The rate can change on January 1, April 1, July 1, and October 1. A change only affects interest going forward; interest already accrued in a prior quarter stays put.
Two features make the cost grow faster than most people expect. First, the interest compounds daily, so each day’s calculation includes all previously accrued interest and penalties, not just the original tax. Second, the clock starts on the original due date of the return, not on the day you enter the payment plan. A filing extension gives you more time to submit paperwork but does not push back the payment deadline.3Internal Revenue Service. Interest
Paying the balance in full is the only way to stop interest. No payment plan, hardship status, or penalty waiver stops the interest clock while you still owe money.
The Penalty That Stacks on Top
Interest is only part of the cost. The IRS also charges a failure-to-pay penalty of 0.5% of the unpaid tax for each month or partial month the balance is outstanding, capped at 25%.4Internal Revenue Service. Failure to Pay Penalty Once you have an approved installment agreement and you filed your return on time (including extensions), that rate drops to 0.25% per month.2Office of the Law Revision Counsel. 26 U.S. Code 6651 – Failure to File Tax Return or to Pay Tax File late and you forfeit that reduction, even if you later set up a plan.
Interest also accrues on the penalties themselves, so a late balance grows on three fronts at once: original tax, penalties, and interest on both.
If You Haven’t Filed at All
If the return isn’t filed, a separate failure-to-file penalty runs at 5% per month, also capped at 25%.5Internal Revenue Service. Failure to File Penalty That’s ten times the failure-to-pay rate. File on time even if you cannot pay: it stops the larger penalty and preserves your access to the reduced 0.25% rate once the plan is in place.
What It Costs on a Real Balance
At the current 7% rate compounded daily, combined with the reduced 0.25% monthly penalty available under an installment agreement, a $10,000 tax debt grows by roughly $100 or more in the first month alone. Stretched across a 72-month installment agreement, the combined interest and penalties can run into the thousands on top of the original balance. The exact number depends on how quickly you pay down the principal and whether the quarterly rate shifts along the way.
The practical implication is simple. Every extra dollar you can put toward the balance shrinks the principal that daily interest compounds against, so the return on a prepayment is real and immediate.
Ways to Bring the Cost Down
Pay Extra Whenever You Can
The IRS does not penalize overpayment on an installment agreement. Any amount above your scheduled monthly payment goes straight to the principal, which means less interest tomorrow and every day after. A bonus, a tax refund from another year, or a good month at work all move the finish line closer.
Speaking of refunds: while your plan is active, the IRS automatically applies any future tax refunds to your outstanding balance until the debt is paid.6Internal Revenue Service. Payment Plans; Installment Agreements Your monthly payment is still due in the months a refund is applied, so don’t plan on the offset covering an installment. The upside is that each offset knocks down principal and reduces interest going forward.
Ask for Penalty Abatement
The IRS can remove or reduce the failure-to-pay penalty in two situations. First Time Abatement is available if you filed the same type of return for the prior three tax years, had no penalties during those years (or any penalty was removed for an acceptable reason), and haven’t previously received First Time Abatement relief.7Internal Revenue Service. Administrative Penalty Relief Reasonable cause relief is the other route, where you show that circumstances such as serious illness or a natural disaster prevented timely payment. Either request can be made by phone or in a letter.
Penalty abatement has a bonus effect: when the IRS removes a penalty, it also recalculates interest without the abated amount, so you get back some of the interest that had been running on top of that penalty.
Don’t Count on Interest Abatement
Interest itself is almost never reduced. The IRS will abate interest only when an IRS employee’s unreasonable error or delay caused it to accrue, and only for the specific period tied to that error.8Internal Revenue Service. Interest Abatement Financial hardship, not knowing the rules, and relying on a tax preparer are not grounds for interest abatement. Treat the interest charge as fixed and put your effort into paying down principal and pursuing penalty relief.
Staying in Good Standing
The reduced 0.25% monthly penalty rate only lasts while your installment agreement is in good standing. Default on the plan and the rate springs back to 0.5%. After a default notice, you have a 30-day window to respond before the IRS can terminate the agreement and move to collection actions, including levies on bank accounts or wages and filing a Notice of Federal Tax Lien.9Internal Revenue Service. 5.14.11 Defaulted Installment Agreements
Three things keep the plan alive: make every scheduled payment on time, file every future return by its due date, and pay any new tax balance in full when it comes due. A missed current-year return can default the existing agreement even if every monthly installment has been paid on schedule.6Internal Revenue Service. Payment Plans; Installment Agreements If your finances change, call the IRS and modify the plan before you miss a payment. Reworking an active agreement is far easier than reinstating a defaulted one, and it protects the reduced penalty rate that saves you money every month.