Quick answer
The underpayment penalty (also called the estimated tax penalty) applies when you didn’t pay enough tax during the year through withholding or quarterly estimated payments. It works like interest: in late 2026 the rate is 7% a year, compounded daily, charged on each quarter’s shortfall from its due date until you pay. For most freelancers it’s a few hundred dollars, not a disaster, but it’s easy to avoid.
When does it apply?
You may owe it if both are true:
- You owe $1,000 or more when you file (after withholding and credits), and
- Your withholding and on-time payments were less than 90% of this year’s tax and less than 100% of last year’s (110% if your AGI was above $150,000).
It’s calculated quarter by quarter, so paying late in the year doesn’t fully fix earlier missed payments.
How it’s calculated
Formula: Penalty ≈ shortfall × IRS rate × (days late ÷ 365)
The IRS rate is the federal short-term rate plus 3 percentage points, set every quarter. It’s 7% for the fourth quarter of 2026.
Example: skipping all four payments
Alex should have paid $1,000 each quarter in 2026 but paid nothing until filing on April 15, 2027:
| Payment due | Shortfall | Days late | Penalty (7%, daily compounding) |
|---|---|---|---|
| April 15, 2026 | $1,000 | 365 | $72.50 |
| June 15, 2026 | $1,000 | 304 | $60.03 |
| September 15, 2026 | $1,000 | 212 | $41.49 |
| January 15, 2027 | $1,000 | 90 | $17.41 |
| Total | $4,000 | about $191 |
The example assumes the rate stays at 7% for the whole period; the IRS applies each quarter’s actual rate.
Don’t confuse it with other penalties
| Penalty | When it applies | Rate |
|---|---|---|
| Underpayment (estimated tax) | Not enough paid during the year | Interest-like, 7% a year in late 2026 |
| Failure to pay | Balance not paid by the April filing deadline | 0.5% of unpaid tax per month, up to 25% |
| Failure to file | Return filed late without an extension | 5% of unpaid tax per month, up to 25% |
The failure-to-file penalty is by far the most expensive. Always file on time or request an extension, even if you can’t pay.
How to fix it if it’s already happened
- Pay what you owe as soon as possible. The penalty keeps growing daily until the shortfall is paid. Use IRS Direct Pay.
- Let the IRS calculate it, or calculate it yourself. Most tax software fills out Form 2210 automatically. You can also skip the form and the IRS will send you a bill.
- Check the annualized income method (Form 2210, Schedule AI) if most of your income came late in the year. It often reduces or eliminates the penalty.
- Request a waiver if you qualify (see below).
- If you can’t pay the full balance, set up a payment plan. Interest continues, but it stops the failure-to-pay penalty from growing as fast. See IRS Payment Plans.
Can the underpayment penalty be waived?
The IRS may waive it if:
- The underpayment was due to a casualty, disaster or other unusual circumstance and it would be inequitable to impose the penalty.
- You retired after age 62 or became disabled during the year or the previous year, and the underpayment was due to reasonable cause, not willful neglect.
You request the waiver on Form 2210 with an explanation. The «first-time abatement» relief that applies to some other penalties generally does not apply to the estimated tax penalty.
How to avoid it next year
- Use the safe harbor: pay 100% (or 110%) of this year’s total tax in four equal payments next year. See The Safe Harbor Rule.
- Set calendar reminders for April 15, June 15, September 15 and January 15.
- Automate savings: move 25-30% of every payment into a tax account.
- If you have a W-2 job, raise your withholding; it counts as paid evenly through the year.
Frequently asked questions
How much is the underpayment penalty?
It’s interest-like: 7% a year (late 2026) on each quarter’s shortfall for the time it was late. On a $4,000 shortfall spread over the year, it’s roughly $190.
I got a refund. Can I still owe an underpayment penalty?
It’s unlikely, but possible if you paid late in the year: the penalty depends on when you paid, not only how much.
Is the underpayment penalty tax deductible?
No. Federal tax penalties aren’t deductible.
Do I owe it in my first year of freelancing?
Not if you had no tax liability in the previous full year. From the second year, the normal rules apply.
This article is general information, not tax advice. Consult a CPA or Enrolled Agent for your situation.
Sources
- Interest rates remain the same for the fourth quarter of 2026 (IRS): 7% rate, compounded daily, federal short-term rate + 3%.
- Payment plans; installment agreements (IRS): payment plan options.
Thresholds, waivers, Form 2210 and Schedule AI come from the Form 2210 instructions and IRS Topic 306; failure-to-file and failure-to-pay rates come from IRS penalty guidance. The example is a FreelancerTaxHQ calculation.