Key Insights
- The 2026 IRS underpayment interest rate is 8% per year, compounded daily.
- Interest runs on both unpaid tax and accrued penalties — it does not stop when you enter a payment plan.
- Penalties can often be reduced or eliminated; interest generally cannot.
- Paying off your IRS debt faster — or in a lump sum via Offer in Compromise — is often the lowest total-cost path.
What Is the Current IRS Interest Rate?
The IRS charges interest on all underpayments of tax — including balances on installment agreements — at the federal short-term interest rate plus 3 percentage points, compounded daily. As of 2026, this puts the annual rate at 8%.
This rate is recalculated each quarter based on the federal short-term rate announced by the IRS. If federal rates fall, the IRS rate can drop. If they rise, it can increase.
2026 IRS Interest Rate
8% per year
Federal short-term rate (5%) + 3 percentage points. Compounded daily. Applies to all individuals with unpaid tax.
How IRS Interest Is Calculated
IRS interest compounds daily. That means every day your balance is unpaid, interest accrues on the principal plus all previously accrued interest and penalties. Over a year, this results in an effective annual rate slightly above the stated rate.
Interest starts accruing on the due date of the return — typically April 15 — not on the date you receive a notice. If you filed an extension, interest still starts April 15; the extension only delays the filing deadline, not payment.
Interest also applies to unpaid penalties. So if you have a failure-to-pay penalty sitting on your account, interest is building on that penalty balance too.
Does an Installment Agreement Stop Interest?
No. Entering an IRS installment agreement stops collection enforcement — levies, wage garnishments, and bank seizures pause while you are in good standing on your agreement. But it does not stop interest from accruing.
The failure-to-pay penalty does reduce from 0.5% per month to 0.25% per month while you are in an active installment agreement. That's meaningful, but interest still runs at the full rate on the outstanding balance.
The practical implication: a $30,000 IRS balance on a 72-month payment plan at 8% interest will cost significantly more than $30,000 by the time it's paid off. Paying it down faster — even if it means stretching your budget — saves money.
Strategies to Reduce Your Total Cost
Request penalty abatement
Penalties are much easier to remove than interest. If you qualify for First-Time Penalty Abatement or have a reasonable cause, eliminating penalties shrinks the balance on which interest compounds.
Pay as much as possible upfront
Every dollar you pay upfront is a dollar that stops accruing daily compounding interest. If you can make a larger initial payment when setting up your installment agreement, do it.
Explore an Offer in Compromise
If your financial situation qualifies, an accepted OIC settles the entire debt — principal, penalties, and interest — for a lump sum or short-term payments. This eliminates the ongoing interest accrual completely.
Consider a third-party loan
A personal loan or home equity line at a rate below 8% may be less expensive than maintaining an IRS payment plan. This is a financial calculation worth running with a professional.
Frequently Asked Questions
Yes. The IRS interest rate is set quarterly based on the federal short-term rate plus 3%. In 2026 the rate is 8% annually (compounded daily). It can increase or decrease each quarter based on federal rate changes.
Generally no — the IRS has very limited authority to waive interest. Interest abatement is only available in narrow circumstances, such as IRS error or delay that caused the interest to accrue. Penalties are much easier to remove than interest.
Entering an installment agreement stops the failure-to-pay penalty from accumulating at the standard rate. However, it does not eliminate penalties that have already accrued, and interest continues throughout the payment plan.
In most cases, yes. Since interest compounds daily, paying more each month reduces your total cost significantly. If you have savings or can access funds at a lower interest rate (such as a personal loan), using them to pay off IRS debt early often makes financial sense.