State Guide

How to Appeal Your Property Taxes in Delaware (2026 Guide)

Published July 27, 2026

If you own a home in Delaware, your county sets its assessed value — and for the first time in decades, that number is supposed to be what your home is actually worth. Delaware just finished reassessing every property in all three counties, replacing base years that had gone stale since 1974 (Sussex), 1983 (New Castle), and 1987 (Kent). That reset changes both how you read your assessment and how you challenge it.

The Delaware deadline: three counties, three dates

Delaware has no single statewide appeal deadline. Each county runs its own Board of Assessment Review, and the dates are genuinely different:

County	Annual appeal deadline	Board hears appeals
New Castle	Before March 15 (the county publishes March 14) — 9 Del. C. §8311(a)	On a schedule set by the Board
Kent	Received by January 31 — affects the tax year beginning June 1	Spring
Sussex	March 15 application deadline	March 1 – May 31

Kent is the one that catches people out: its deadline lands six weeks before the other two, and appeals must be received — Kent does not accept postmarks, and it moves the date when January 31 falls on a weekend. Sussex likewise requires applications in hand by 4:30 p.m., not postmarked.

A mid-year supplemental (quarterly) assessment increase is a separate appeal from the annual one. Kent sets that window explicitly: 30 days from the notice of increase. Sussex also treats it separately but publishes no fixed window — and narrows the scope, letting you challenge only the amount by which your assessment rose that quarter. If a supplemental notice arrives, call your county the same week rather than assuming the annual date applies.

Confirm your exact date and cutoff time with your county before you rely on it — these are county-administered dates, and 2026 and 2027 both put several of them on a weekend.

How Delaware assesses your home

Under 9 Del. C. §8306(a), all property is assessed at its fair market value as of the date of the most recent reassessment base year in the county. Delaware is not a fractional-assessment state — your assessed value is meant to be market value, so you compare it to comparable sales directly.

Category	Delaware
Assessment basis	100% fair market value as of the county's reassessment base year (§8306(a))
Base year	Kent July 1, 2023 · Sussex July 1, 2023 · New Castle July 1, 2024
Reassessment cycle	At least every 5 years (§8306(b), added by HB 62 in 2023)
Assessment cap	None on your individual value — §8002 limits the county's revenue, not your assessment
Where you file	Your county Board of Assessment Review
Next step	Superior Court, within 30 days of the decision (§8312)

Two traps worth naming. First, never divide your assessment by an old fraction. Delaware's pre-reassessment system quoted values against frozen base years — Kent, for instance, billed on 60% of a 1987 value — and applying any of those legacy fractions to today's number manufactures an over-assessment that isn't there. Second, the standard is the base-year market, not today's market. A New Castle appeal is judged on what your home was worth on July 1, 2024; Kent and Sussex on July 1, 2023. Appreciation since then is not by itself a ground for appeal — and it is not a defense against one, either.

There is no cap protecting your bill in Delaware. 9 Del. C. §8002 makes counties compute a rolled-back rate after a reassessment and limits county property tax revenue growth to 15% over the prior year — but that is a county-wide levy limit, not a ceiling on your individual value. The practical upside: a reduction you win flows straight through to your bill, undamped.

What wins a Delaware appeal

The counties are explicit about the bar. Sussex's Board rules require the owner to present competent evidence of substantial overvaluation — if you don't, the Board may deny the appeal without hearing further testimony. That means closed comparable sales near your county's base date, for homes genuinely like yours in size, age, and condition, with the differences adjusted rather than hand-waved. It does not mean your tax bill went up, or that a neighbor pays less.

Expect a real hearing, not a formality: residential appeals in Sussex are typically limited to 15 minutes per side when neither party brings an appraiser, testimony is under oath, and the county's assessor may present evidence supporting either the assessment of record or a lower value. Delaware's constitution also requires that taxes be uniform upon the same class of subjects (art. VIII, §1), so a well-documented inequity argument has a footing alongside straight overvaluation.

One caution: Delaware's statutes let assessment bodies revise valuations in either direction (§8302), and §8311 empowers boards to make "additions, alterations or corrections." In practice, New Castle and Sussex both describe the outcome of an owner's appeal as reducing or affirming the assessment — but an assessor does review your property and its record data as part of the process, so file when your comps genuinely support a lower value, not as a free roll of the dice. If the Board rules against you, §8312 gives you 30 days to appeal to Superior Court, where the Board's decision is prima facie correct and the burden is on you.

Get your case built

Delaware's reassessment reset every value in the state, and plenty of them landed wrong. PROppeal pulls licensed comparable sales for your address, weighs them against your county's base-year standard rather than a misleading present-day comparison, and gives you a straight answer on whether your assessment is genuinely out of line — before your county's deadline arrives.

Property tax rules and deadlines vary by jurisdiction and can change — verify with your county before relying on this.