Delaware property taxes (2026)

How Delaware property taxes work

Delaware's three counties — New Castle, Kent, and Sussex — collect property tax for themselves and the school districts, with some of the lowest effective rates in the country. The traditional due date is September 30 (New Castle also bills a spring installment), but check current bills: reassessment fallout has moved deadlines recently, including New Castle's 2026 extension to December 31.

The big story is reassessment: court-ordered revaluations gave all three counties their first new values in decades, and the appeal machinery is running hot — thousands of appeals a year in New Castle alone. New values mean the old 'nobody appeals in Delaware' rule is gone.

Appeals are county-run: generally a written appeal to the county's assessment office or Board of Assessment Review within roughly 30 days of an assessment notice, with annual windows for ongoing appeals — each county posts its own calendar.

The Senior School Property Tax Credit takes 50% off school taxes (up to the cap) for homeowners 65+ with a few years of Delaware residency — an April 30 application through your county — and each county adds its own senior/disability exemptions under local rules.

When payments are due

Traditionally due September 30 (New Castle splits fall/spring) — but reassessment-era extensions apply; your county's current bill controls.

Exact dates can vary by county — use your county's page above for the dates on your bill.

How to appeal your assessment

The statewide rule: File a written appeal with your county's assessment office within its posted window — generally about 30 days from an assessment notice, with annual appeal periods for standing values

Post-reassessment, each county runs a formal appeal season announced with the notices. Evidence is market value as of the county's reassessment base date — check which date your county uses.

1. Read your assessment noticeReassessment-era notices show the new full market value and the appeal instructions and deadline for your county.
2. Start with the informal reviewEach county's assessment office (and its reassessment contractor) offers informal reviews that fix errors fastest.
3. File the written appeal by your county's deadlineTo the county Board of Assessment Review — free or nominal fee, forms on the county site.
4. Attend the hearingBring comparable sales near the county's base valuation date.
5. Escalate if neededBoard decisions can be taken to superior court.

County pages have the exact local deadlines, forms, and filing links.

Statewide exemptions

Reassessment

All three counties completed their first general reassessments in decades in the mid-2020s and are standing up regular cycles — expect values (and appeal seasons) to move more often than Delaware homeowners are used to.

Value notices (Assessment notice) usually mail in spring (notice waves during the cycle).

Common questions

When are property taxes due in Delaware?

The traditional date is September 30 — but reassessment turbulence has moved deadlines (New Castle pushed its 2026 bills to December 31), so treat your county's current bill as the authority.

How do I appeal my Delaware assessment?

File a written appeal with your county's assessment office in its posted window — roughly 30 days from your notice, with annual appeal seasons since the reassessments. Informal reviews with the county fix errors fastest.

Why did my Delaware assessment suddenly change after decades?

Court-ordered reassessment: all three counties revalued for the first time in 40+ years. New values are supposed to be revenue-neutral overall, but individual bills moved both directions — which is exactly what the appeal seasons are for.

What is the Senior School Property Tax Credit?

Homeowners 65+ get 50% off school property taxes up to the cap, after meeting Delaware residency rules. One application by April 30 with your county — and it keeps renewing.

Are Delaware property taxes really that low?

Effective rates are among the nation's lowest, and there's no state sales tax either. School taxes are most of the bill — which is why the senior school credit is the relief that matters most.