N-210: Underpayment of Estimated Tax by Individuals, Estates and Trusts (2025)

Who files this form

Form N-210 covers underpayment of estimated tax by individuals, estates, and trusts.

The form directs you to check the applicable boxes and file it with your tax return if:

• Box A: You were a full-year Hawaii resident in 2024, an estate for a Hawaii decedent, or a Hawaii trust; you had no 2024 tax liability; and your 2024 tax year covered 12 months. If all these conditions apply, you do not owe the penalty.
• Box B: You request a waiver of the penalty.
• Box C: You use the annualized income installment method.
• Box D: You treat Hawaii income tax withheld from wages as paid when actually withheld, rather than equally on the payment due dates.
• Box E: One or more required installments are based on your 2024 tax, and you filed or are filing jointly for either 2024 or 2025, but not both years.

Line 5 also says that if your 2025 tax liability minus credits and Hawaii income tax withheld is less than $500, stop. Do not complete or file the form, and no penalty is owed.

When it's due

For tax year 2025, the form prints these estimated tax payment due dates:

• April 20, 2025
• June 20, 2025
• September 20, 2025
• January 20, 2026

For the 2025 penalty calculation, line 18 uses the date the underpayment was paid or April 20, 2026, whichever is earlier. This is a penalty calculation cutoff, not a separately stated filing deadline for Form N-210.

What you'll need

Have these returns and information available to complete the form:

• Your 2025 Form N-11, N-15, or N-40, including your name, Social Security number or FEIN, tax liability, credits, and Hawaii income tax withheld.
• Your 2024 income tax return for the prior-year tax amount requested on line 7.
• The amounts and dates of your estimated and other tax payments.
• If using Schedule A, your income, deductions, exemptions, other taxes, and credits for the periods shown. Estates and trusts use taxable income without their exemption on Schedule A, line 1.

How to file

Attach Form N-210 to Form N-11, N-15, or N-40. Check every applicable box in the Reasons for Filing section.

Enter the total penalty from line 21 on:

• Form N-11, line 50;
• Form N-15, line 67; or
• Form N-40, Schedule G, line 8.

The supplied form does not give a mailing address or e-filing directions.

Common mistakes

• Leaving required boxes unchecked: The form says to check the applicable Reasons for Filing boxes and file it with your return. This includes Box A even though that exception eliminates the penalty.
• Continuing when line 5 is less than $500: The form says to stop and not complete or file Form N-210.
• Working across columns too soon: Complete lines 11 through 17 in one column before starting line 11 in the next. On Schedule A, complete lines 19 through 24 in one column before moving to the next.
• Using the individual Schedule A periods for an estate or trust: Estates and trusts must instead use period ending dates of February 28, April 30, July 31, and November 30, 2025.
• Overlooking the line 10 stopping rule: If line 10 is at least line 9 for every payment period, stop. No penalty is owed.

Questions people ask

Can I request a waiver of the penalty?

Yes. Check Box B to request a waiver. The form says the Department of Taxation will waive all or part of the penalty in certain circumstances, but refers to separate instructions for details.

What if my income varied during 2025?

The annualized income installment method may reduce one or more required installments. Check Box C and use Schedule A, carrying the amounts from line 24 to Part III, line 9.

How is the penalty calculated?

For each payment period, line 20 multiplies the number of months on line 19 by .00667 and the underpayment on line 16. Add the amounts for all columns on line 21. If there are no entries on line 16, no penalty is owed.

Do references to spouses include civil union partners?

Yes. The form says references to “married” and “spouse” also refer to “in a civil union” and “civil union partner,” respectively.

Official sources

• https://files.hawaii.gov/tax/forms/current/n210_i.pdf