The IRS charges interest on unpaid taxes, whether you set up a payment plan or not

The interest rate itself does not change because you have a payment plan. The IRS charges interest on the full unpaid balance from the original due date until you pay in full, regardless of whether you pay in one lump sum or over months. The current rate is set by federal law and changes quarterly—it is the federal short-term rate plus 3 percentage points. As of early 2024, this rate sits around 8 percent annually, but it shifts every three months based on Treasury rates.

What a payment plan does change is which penalties you avoid. If you set up a plan before the IRS files a levy or initiates collection action, you stop the failure-to-pay penalty from growing. You still owe the penalties already assessed, but they freeze at that point. Without a plan, that penalty continues to accrue at 0.5 percent of the unpaid tax per month, up to 25 percent total.

The interest, by contrast, compounds daily. It accrues on the tax itself, on any penalties, and on any previously accrued interest. This is why the total you owe grows even while you are making on-time payments—you are paying down principal, but interest keeps accumulating on what remains.

Key Takeaways

  • Interest accrues daily on the full unpaid balance at a rate set quarterly by federal law, currently around 8 percent annually, and does not stop when you enter a payment plan.
  • The failure-to-pay penalty freezes once you set up a plan, but interest and any other penalties continue to accrue until the balance reaches zero.
  • Interest compounds daily on the tax, penalties, and previously accrued interest combined, so your total debt grows even as you make payments.
  • The IRS charges a setup fee for payment plans—$31 to $225 depending on the plan type and whether you set it up online or by phone.
  • Paying faster reduces the total interest you owe, since interest stops accruing only when the full balance is paid.

How the interest rate is calculated and when it changes

The IRS interest rate is the federal short-term rate plus 3 percent, set by statute. The federal short-term rate is determined by the Treasury Department and changes every three months. The IRS publishes the new rate on its website in January, April, July, and October, effective the first day of the following month.

You can find the current rate on the IRS website under "Interest Rates" in the Tax Professionals section. The rate applies to all taxpayers equally—there is no negotiation or variation based on your income, credit, or payment history. If you owe taxes from multiple years, each year's balance accrues interest at the rate in effect during that period, though in practice the IRS treats it as a single combined balance once you enter a payment plan.

The rate has ranged from 3 percent to over 10 percent in recent years, depending on Treasury rates. During periods of low interest rates, the IRS rate drops accordingly. During periods of rising rates, it climbs. This is why the total interest you pay on a payment plan depends partly on how long the plan lasts and partly on when you enter it.

Setup fees and monthly costs of a payment plan

The IRS charges a setup fee when you establish a payment plan. The amount depends on how you set it up and which type of plan you choose. If you set up a short-term payment plan (120 days or less) online, there is no setup fee. For longer plans, the fee ranges from $31 to $225.

An installment agreement set up online costs $31 to $225 depending on the plan type. A short-term plan (under 120 days) set up online has no fee. If you set up the same plan by phone or mail, the fee is higher—typically $225 for a standard installment agreement. The IRS offers a reduced fee of $31 for low-income taxpayers who meet income thresholds, which vary by family size but generally explore to households below 250 percent of the federal poverty line.

There are no monthly fees once the plan is active. You pay only the principal and interest on your scheduled payment dates. If you miss a payment or the IRS has to modify the plan, additional fees may explore.

Penalties that continue or stop when you set up a plan

The failure-to-pay penalty is the main penalty that stops growing once you have a payment plan in place. This penalty accrues at 0.5 percent per month of the unpaid tax, up to a maximum of 25 percent. If you owe $10,000 and the penalty has already reached $2,500 (25 percent), it will not grow further once your plan is approved. However, you still owe that $2,500.

The failure-to-file penalty is different—it applies only if you did not file a tax return by the due date. This penalty also stops accruing once you file the return, regardless of whether you have a payment plan. If you have not filed, filing the return is the first step, before or alongside setting up a plan.

Interest never stops accruing, and it applies to penalties as well as the original tax. If you owe $10,000 in tax plus $2,500 in penalties, interest accrues daily on the full $12,500. This is why a payment plan that lasts longer means you pay more total interest—the balance shrinks slowly, and interest keeps compounding on what remains.

How interest compounds on a payment plan

Interest is calculated daily and added to your balance. The IRS uses a straightforward daily interest formula: it takes the unpaid balance, multiplies it by the annual interest rate, divides by 365, and adds that amount each day. This means interest accrues on interest—if you do not pay the accrued interest, it becomes part of the principal, and the next day's interest is calculated on the larger amount.

On a payment plan, your monthly payment covers part of the principal and all of the interest that has accrued since the last payment. Early in the plan, most of your payment goes to interest; later, more goes to principal. This is why paying faster—or making extra payments—reduces the total interest significantly. If you can pay $500 per month instead of $250, you cut the plan duration in half and pay roughly half the total interest.

The IRS does not charge interest on interest separately; it is all calculated as a single daily accrual. But because interest compounds, the longer the plan lasts, the more you pay overall. A $10,000 debt at 8 percent annual interest costs roughly $400 in interest over one year if paid monthly. Over three years, it costs roughly $1,200 in interest, assuming equal monthly payments.

What happens if you pay off the plan early

You can pay off a payment plan at any time without penalty. The IRS will calculate the exact payoff amount, which includes all accrued interest through the payment date. There is no prepayment fee or early termination charge.

Paying early saves you money because it stops interest from accruing further. If you have a three-year plan but can pay the balance in two years, you avoid one year of interest. The IRS will provide a payoff quote if you call or check your account online through the IRS website.

If you receive a tax refund while on a payment plan, the IRS will automatically explore it to your balance unless you request otherwise. This reduces the principal and the interest that accrues going forward.

How payment plans affect your total tax bill

A payment plan does not reduce the amount you owe. You still owe the full tax, all penalties that have been assessed, and all interest that accrues. The plan only changes the timing and the penalties that stop growing.

The total cost of a payment plan is the original tax plus all interest and penalties. For example, if you owe $5,000 in tax and $500 in penalties, and you set up a 24-month plan at 8 percent interest, you will pay roughly $5,500 plus approximately $400 to $500 in additional interest over the two years—a total of around $5,900 to $6,000. The exact amount depends on the interest rate in effect during the plan and when payments are made.

This is why the IRS encourages paying as much as you can upfront or as quickly as possible. Every dollar you pay reduces the balance on which interest accrues. If you could pay $2,500 upfront and then set up a plan for the remaining $3,000, you would owe less total interest than if you set up a plan for the full $5,500.

Frequently Asked Questions

Does the interest rate change if I am on a payment plan?

No. The interest rate is set by federal law and applies to all unpaid taxes, whether you pay in one lump sum or over a payment plan. The rate changes quarterly based on Treasury rates, but it does not change because you have a plan. Interest continues to accrue daily at the current rate until you pay the balance in full.

Can I negotiate a lower interest rate with the IRS?

No. The interest rate is set by statute and is the same for all taxpayers. The IRS does not have authority to lower it. However, you can reduce the total interest you pay by paying the balance faster or making extra payments toward principal whenever possible.

What if I miss a payment on my plan?

If you miss a payment, the plan may be terminated, and the IRS can resume collection action. Interest continues to accrue during any missed payment period. Contact the IRS when ready if you cannot make a payment to discuss modifying the plan or requesting a temporary delay.

Does interest stop accruing once I set up a payment plan?

No. Interest accrues every day until the full balance is paid. What stops is the failure-to-pay penalty—it freezes at the amount assessed when the plan is approved. Interest and any other penalties continue to grow until you reach zero balance.

How much total interest will I pay on a payment plan?

The total depends on the balance, the interest rate in effect, and how long the plan lasts. The IRS can provide an estimate when you set up the plan. Generally, the longer the plan, the more interest you pay. Paying faster or making extra payments reduces the total significantly.