Hilo taxpayers file a Hawaii income-tax return in addition to a federal return. Hawaii starts with federal concepts, but its own forms, rates, deductions, credits, deadlines, and extension rules control the state filing. This guide summarizes the major differences for individuals, partnerships, S corporations, and C corporations. Always check the current Hawaii Department of Taxation instructions for the year you are filing.
Hawaii versus federal tax: the basic difference
The IRS administers federal income tax using federal Form 1040, Form 1065, Form 1120-S, or Form 1120. Hawaii uses its own returns, including Form N-11 for residents, Form N-15 for nonresidents and part-year residents, Form N-20 for partnerships, Form N-35 for S corporations, and Form N-30 for corporations. A federal extension does not replace the Hawaii extension process.
Hawaii may begin with federal adjusted gross income or federal taxable-income concepts, then require state additions, subtractions, exemptions, credits, and Hawaii-specific schedules. A federal refund does not guarantee a Hawaii refund, and a federal extension does not extend the time to pay Hawaii tax.
Hawaii individual income-tax rates
For taxable years beginning after December 31, 2024, Hawaii’s individual rate schedules range from 1.40% to 11.00%. The brackets depend on filing status. The rate schedule below is a high-level guide; taxpayers with taxable income under the Department’s threshold should use the official Hawaii tax table rather than simply multiplying income by a marginal rate.
| Taxable-income range (single schedule) | Marginal rate |
|---|---|
| Up to $9,600 | 1.40% |
| $9,600–$14,400 | 3.20% |
| $14,400–$19,200 | 5.50% |
| $19,200–$24,000 | 6.40% |
| $24,000–$36,000 | 6.80% |
| $36,000–$48,000 | 7.20% |
| $48,000–$125,000 | 7.60% |
| $125,000–$175,000 | 7.90% |
| $175,000–$225,000 | 8.25% |
| $225,000–$275,000 | 9.00% |
| $275,000–$325,000 | 10.00% |
| Over $325,000 | 11.00% |
Joint-return and head-of-household thresholds are generally wider, but the same rate structure should be calculated from the applicable Hawaii schedule. Hawaii’s standard deduction and personal-exemption amounts also differ from federal amounts and can change by tax year.
Individual filing deadlines and extensions
- Hawaii individual deadline: April 20 for calendar-year individuals, rather than the federal April 15 deadline.
- Hawaii automatic extension: Hawaii generally allows an automatic six-month extension to file Form N-11 or N-15 when the taxpayer is due a refund or pays the properly estimated Hawaii tax by April 20. The resulting filing deadline is generally October 20.
- Payment is not extended: An extension gives more time to file, not more time to pay. Underpaying the estimated amount can eliminate the automatic extension and trigger penalties and interest.
- Federal Form 4868: Hawaii does not accept the federal Form 4868 as a substitute for Hawaii’s requirements.
Federal calendar-year individuals generally file by April 15, with a federal extension to October 15. Those dates do not replace Hawaii’s April 20 and October 20 framework.
Partnership and corporate deadlines
- Hawaii partnership Form N-20: generally due on the 20th day of the fourth month after the close of the taxable year. A calendar-year partnership typically looks to April 20.
- Hawaii corporation Form N-30: generally due on the 20th day of the fourth month after the close of the taxable year. A calendar-year corporation typically looks to April 20.
- Hawaii S corporation Form N-35: generally follows the state’s 20th-day-of-the-fourth-month rule unless a specific instruction or tax-year exception applies.
- Federal comparison: a calendar-year partnership and S corporation generally file federal returns by March 15, while a calendar-year C corporation generally files Form 1120 by April 15. Hawaii’s state deadline is not automatically the same as the federal deadline.
Fiscal-year entities count forward from the end of their own tax year. Confirm the due date, extension form, estimated-payment requirement, and composite or nonresident-owner obligations for the entity’s exact facts.
How Hawaii can diverge from the IRS
- Different starting point: Hawaii may require state additions or subtractions even when the federal return is correct.
- Different deductions and exemptions: Hawaii standard deductions, personal exemptions, credits, and itemized-deduction limits do not simply mirror federal figures.
- Different filing calendar: April 20 and the state’s 20th-day-of-the-fourth-month entity rule are distinct from many federal due dates.
- Separate extensions: federal Form 4868 does not substitute for Hawaii’s extension requirements.
- Different disaster relief: state relief can be announced separately from IRS relief and may require a Hawaii form or case-by-case request.
Hilo taxpayer checklist
- Prepare the federal return first, then reconcile it to Form N-11, N-15, N-20, N-30, or N-35.
- Mark April 20 for calendar-year Hawaii returns and pay estimated tax by that date if using the automatic extension.
- Track federal and Hawaii estimated payments separately.
- For businesses, document the taxable year-end and calculate the 20th day of the fourth month.
- Check current Hawaii Department of Taxation instructions for rate schedules, disaster relief, and electronic-filing requirements.
Bottom line
Hilo residents and businesses must treat Hawaii filing as a separate compliance project—not a copy of the federal return. The rates, forms, deadlines, extensions, and payment rules can diverge from the IRS. This guide is educational and should be verified against current Hawaii instructions and professional advice before filing.
