IRS Payment Plan Interest Rate: What You Really Pay in 2026

Two separate charges accrue on an unpaid balance during an installment agreement, and they work differently:

Charge	Rate inside a plan	How it accrues	Cap
Underpayment interest	7% per year (Q3 2026)	Compounded daily on tax, penalties, and previously accrued interest	None, runs until paid
Failure to pay penalty	0.25% per month (3% per year), reduced from 0.5% because the plan is approved and the return was filed on time	Simple, charged monthly on the unpaid tax only	25% of the tax, lifetime

The reduced penalty rate is a real, published benefit of getting a plan approved: without one, the penalty runs 0.5% per month, and it jumps to 1% per month if you ignore an intent to levy notice. The daily compounding on interest matters too. A 7% annual rate compounded daily works out to an effective 7.25% per year, and because interest accrues on penalties and on prior interest, the true base grows slightly faster than the tax alone.

Take a $20,000 balance entering a payment plan today, before any monthly payments:

• Interest: 7% compounded daily is an effective 7.25%, about $1,450 over a full year on a static $20,000.
• Failure to pay penalty: 0.25% of the unpaid tax per month, about $600 over a year if the full balance were tax.
• Combined: roughly $2,050, or about 10.3% of the balance.

In practice you are making payments, so the real cost is lower and front loaded: each payment shrinks the base that both meters run on. The penalty meter also dies twice: it stops when its lifetime 25% cap is reached, and it stops permanently once the tax is paid, while interest runs to the last day. Run your own payoff schedule, with your balance and proposed monthly payment, in our tax debt calculator, and see IRS penalties and interest explained for how the charges are assessed in the first place. If you are not sure what your current balance even is, here is how to find out exactly.

The underpayment rate is set each quarter at the federal short term rate plus 3 percentage points, published in IRS revenue rulings. The recent record, from the IRS quarterly rate tables:

Quarter	Individual underpayment rate
2024 Q1 through Q4	8%
2025 Q1 through Q4	7%
2026 Q1	7%
2026 Q2	6%
2026 Q3	7%
2026 Q4	7% (announced August 2026)

Two takeaways. First, the rate moves with short term Treasury yields, so it will fall if rates broadly fall; nobody locks in an IRS rate, for better or worse. Second, the band has been narrow, 6% to 8%, which makes long range payoff planning reasonably reliable even though the rate technically resets 40 times over a 10 year agreement.

The honest comparison, using current figures:

Way to carry the debt	Approximate annual cost	Notes
IRS installment agreement	~10.3%	7% interest plus 3% reduced penalty; penalty portion eventually caps
Credit card	22.15% average on accounts assessed interest, Federal Reserve G.19, Q2 2026	More than double the IRS cost for most cardholders
Personal loan	Commonly ~7% to 20% depending on credit	Fixed rate and a firm payoff date; strong credit can beat the IRS cost
Home equity borrowing	Often below the IRS combined rate	Cheapest option for many homeowners, but converts unsecured tax debt into debt secured by your home

The clear verdict: never move IRS debt onto a credit card you will carry a balance on. The murkier question is whether to refinance with a loan, covered next.

The arithmetic says refinance whenever your all-in borrowing rate beats roughly 10.3%. The full answer is more nuanced, in both directions:

• Reasons refinancing can win beyond the rate: paying the IRS in full stops the failure to pay penalty immediately, usually prevents or clears a federal tax lien, ends any default risk, and removes the IRS from your life. A fixed loan payment also cannot be revisited the way a financially verified agreement can.
• Reasons to stay with the IRS even at a slightly higher rate: IRS debt is unsecured, and the IRS is a surprisingly flexible creditor. If your income collapses, an installment agreement can be restructured, paused under hardship status, or resolved through an offer in compromise. A home equity lender forecloses. Trading flexible unsecured debt for rigid secured debt to save one or two points is often a bad trade for anyone with volatile income, which describes most founders and 1099 earners.
• Shrink before you compare. If penalties are stacked on your balance, request first time abatement before refinancing anything. Removing an abatable penalty, and its interest, lowers the balance you would borrow; see how first time penalty abatement works.

The complete rules of the plans themselves, thresholds, fees, and default traps, are in our IRS payment plan guide. If you want the refinance-or-ride decision run against your actual numbers, that is exactly the kind of question a free consultation with a resolution specialist on our team is for.