Alaska is unusual: it has no individual income tax and no state sales tax, but it does impose a corporate income tax with the highest top rate of any state. The CPA calendar centers on the corporate return, which is due about a month after the federal date.

Alaska Tax Deadlines at a Glance (2026)

Alaska computes its corporate deadline as 30 days after the federal due date, so a calendar-year C corporation’s Form 6000 is due about May 15, 2026. An S corporation satisfies its requirement by filing Form 6000, page 1 only on the same ~May 15 timeline (Alaska generally imposes no tax on S-corp pass-through items unless a corporate-level tax applies). Partnerships file Form 6900, an information return, roughly April 15 with no entity-level tax. The extension runs to 30 days after the federal extended due date.

The Corporate Income Tax

Alaska’s corporate income tax is graduated from 0% up to a 9.4% top rate (10 brackets; the top rate applies above $222,000) — the highest top corporate rate in the country. There is no elective PTE tax, because Alaska has no individual income tax for one to offset. Alaska also administers a specialized oil and gas production tax, separate from the corporate income tax.

No State Sales Tax — But Local Taxes Apply

Alaska levies no state sales tax, but many boroughs and municipalities impose their own local sales taxes (combined rates average roughly 1.8%). CPAs advising Alaska businesses should track local sales-tax obligations even though there is no state-level equivalent.

CPA Action Steps

• Use ~May 15 for the C-corp Form 6000 (30 days after federal)

• File S-corps on Form 6000, page 1 only, also ~May 15

• File partnerships on Form 6900 (information return, ~April 15)

• Track local sales taxes — there is no state sales tax

Verify current rates and dates against the Alaska Department of Revenue Tax Division (tax.alaska.gov) before filing.