How to Appeal Your Property Tax in Delaware: Step-by-Step Guide for 2026

· ✓ Last verified Oct 3, 2026 · November 13, 2025 · by AskDoss Editorial Team ·Home Services · 7 min read

In Delaware an assessment appeal is a county matter. Each county’s Board of Assessment Review hears it on that county’s own calendar: New Castle County’s statute requires written notice before March 15 (9 Del. C. § 8311(a)), while Kent and Sussex set their own receipt deadlines. A board decision goes to Superior Court within 30 days (§ 8312(c)).

Which Delaware deadline applies to your parcel

Find the county on your bill first. Kent, New Castle and Sussex each published a different cutoff, and none of the three counts a postmark. Every date below is local to the body named in that row.

Step Who hears it Filing rule Authority
Annual appeal, New Castle County Board of Assessment Review of New Castle County Written notice “prior to March 15.” The county lists the 2027 window as January 1 to March 14, 2027, and March 14, 2027 is a Sunday. The county takes appeals through its online filing portal, by email to BOARAppeals@newcastlede.gov, or delivered to the Assessment Division at 87 Reads Way, New Castle. Under the Board’s rules the form must be received by 4:00 p.m.; a postmark does not count. 9 Del. C. § 8311(a); New Castle County BOAR page; BOAR Rules of Procedure, Art. VI § 2 (revised January 21, 2026)
Annual appeal, Kent County Kent County Board of Assessment Review The appeal must be in the Assessment Office by 5:00 p.m. on the last working day in January. In 2027 that is Friday, January 29. Postmarks are not accepted. Supplemental (quarterly) bills are a separate appeal, and Kent publishes two different rules for them. The April 2025 procedures set the last working day in November for the bill dated September 1, February for December 1, and May for March 1. The county’s assessment FAQ says such an appeal “must be filed within 30 days of notification of the increase.” File within 30 days of the supplemental notice to be safe. Kent warns that a reassessment year and the year after may bring different dates. Kent County Appeal Procedures (revised April 2025); Kent County Assessment FAQ; 9 Del. C. § 8311(b) (hearings March 1 to May 31)
Annual appeal, Sussex County Sussex County Board of Assessment Review The Board’s current Rules of Procedure set the deadline at 4:30 p.m. on March 15 each year. The application goes by email to assessmentappeals@sussexcountyde.gov, in person to 2 The Circle, Georgetown, or by mail to PO Box 589, Georgetown, and it must be received by the deadline; a postmark does not count. In 2026 filing opened January 12 and closed March 15. March 15, 2027 is a Monday. Sussex BOAR Rules of Procedure, Art. VIII § 1; Sussex Appeal Procedures & Guidelines (2026); 9 Del. C. §§ 7004(j), 8311(c)
Review of the board’s decision Delaware Superior Court (county set by § 8312(c)) 30 days “by postmark date after receiving notice of its decision.” 9 Del. C. § 8312(c)
City tax on a city assessment (example: Dover) City of Dover Board of Assessment Appeals 2026 forms were due by 5:00 p.m. on April 30, 2026. The city also refused postmarks. City of Dover 2026 assessment notice

The Legislature rewrote the Kent and Sussex hearing periods in 2024 (84 Del. Laws c. 412, HB 403, approved September 19, 2024). Those subsections now read “from March 1 to May 31 of each year or until all appeals have been heard and acted upon during a year of reassessment.” The statute sets when those two boards sit. The filing cutoff comes from each county.

What the board measures: market value on the county’s base date

Section 8306(a) sets the standard: property is “assessed at its fair market value as of the date of the most recent reassessment base year in the county.” After the latest general reassessments, the base dates differ by county.

  • New Castle: July 1, 2024. Its appeal form asks for your opinion of value on that date.
  • Kent: July 1, 2023, per the county’s assessment FAQ.
  • Sussex: July 1, 2023, per its appeal form and guidelines.

A sale you made this year, or a Zestimate, doesn’t answer that question. Kent and Sussex both list online estimates from Redfin, Zillow and similar sites as inadmissible.

Evidence the Delaware boards accept and reject

New Castle and Sussex print the same warning on their residential forms: “The assessed value of other properties, or the taxes paid by other homeowners, is not acceptable as evidence of overvaluation.” Kent’s list of inadmissible evidence includes the old 1987-base assessment and “Assessed Values of properties that are not comparable.” In New Castle and Sussex, pointing to a neighbor’s lower assessment will not carry the appeal. Closed arm’s-length sales and appraisals will.

  • New Castle: cite up to six comparable sales on the form. The Board will not hear sales you left off. An appraisal must come from a Delaware-licensed appraiser and value the home as of the base date, or be prepared within one year before it. Factors not named on the form “will be deemed waived.”
  • Sussex: the form requires three comparable sales. The guidelines accept sales closed January 1, 2021 through June 30, 2023 and appraisals dated January 1, 2022 through June 30, 2023. Distressed, bank-owned, sheriff and family sales are excluded.
  • Kent: the same sale and appraisal windows apply. An appraisal is inadmissible unless the appraiser attends the hearing. A commercial appeal also needs an income and expense statement.

Physical errors, such as wrong square footage, bedroom count or a finished basement that isn’t there, belong on the form with proof. New Castle also corrects factual record errors outside the appeal window. Its reassessment and tax billing FAQ gives assessment@newcastlede.gov and 302-395-5520 for that.

Burden of proof and what happens at the hearing

The New Castle and Sussex rules state the burden in plain terms: “Under State law, there is a presumption Assessment has correctly valued your property.” You must show the assessment is wrong. The county’s assessor has to defend the value only after you present “competent evidence of substantial overvaluation.” In New Castle, the Assessment Office reviews each filing first. It may offer a stipulated lower value, send a deficiency notice with at least ten days to fix it, or schedule a referee or Board hearing. Kent follows a similar path: the assessor reviews the appeal, then a hearing officer (used mainly in reassessment years), then the seven-member Board. Show up for the hearing you are given. In New Castle, missing it “constitutes abandonment of the appeal” (§ 8311(a)). Kent requires you to attend or be represented by an attorney admitted to practice in Delaware, and a no-show is “considered withdrawn and denied.” Sussex also treats a missed hearing as abandonment, but its form has a box to check if you want the Board to decide on the information in the form without a formal hearing.

Superior Court: a review on the record

A board or finance office must mail its decision by registered mail within 30 days of deciding (§ 8312(b)). You then have 30 days by postmark after receiving it to appeal to “the Superior Court of the county in which such person resides” (§ 8312(c)). The court does not start over. The board’s decision is “prima facie correct,” and you must show the board “acted contrary to law, fraudulently, arbitrarily or capriciously.” The court may allow new evidence, and its decision “shall be final.”

Refunds after a reduction

Since 85 Del. Laws c. 133 (HB 240, approved August 12, 2025), § 8311(d) entitles an owner to a refund when a reduction shows an overpayment of $50 or more for the tax year the appeal was filed. Below $50, the county may refund it or credit it against a later bill.

Questions Delaware owners ask

I missed my county’s cutoff. Can I still appeal this year’s value?

No. New Castle and Sussex rules say a late form is held for the next annual appeal period, and any reduction starts with the next tax year. Kent’s procedures say the right to appeal “is lost for the upcoming billing cycle.”

Do I have to be current on taxes to file?

In Kent, yes. Its April 2025 procedures dismiss an appeal “if there is a delinquent balance due,” and the appeal is allowed if the balance is paid by the appeal deadline.

I appealed after the reassessment. Can I file again next year?

Only with something new in Kent and Sussex. Kent dismisses a repeat appeal in the same revaluation cycle “unless evidence of change to the property or new evidence is presented,” and Sussex treats a prior-cycle appeal without new evidence as inadmissible. New Castle’s form asks whether an appeal decision or stipulation changed your value in the last three years.

When will my county reassess again?

Section 8306(b) requires every county to reassess all real property at least once every five years. The five years start when the county certifies a completed general reassessment under § 8314. That subsection was added by 84 Del. Laws c. 162.

Does a city in my county run its own appeal?

Some do, for the city’s own tax. Dover keeps its own assessment list and Board of Assessment Appeals, with a 2026 filing deadline of April 30.

Primary sources: 9 Del. C. ch. 83; New Castle County Board of Assessment Review; Sussex County Board of Assessment Review; Sussex County BOAR Rules of Procedure; Kent County Assessment FAQ; Kent County Appeal Procedures (April 2025).

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