Delaware Property Tax Appeals: Kent, New Castle & Sussex

Delaware Appeals Are Run by the County

Delaware assessment is handled county by county, and the state code points each county to its own procedure. Kent, New Castle and Sussex each run a Board of Assessment Review with its own deadline and form. 9 Del. C. 8301

Looking for Delaware County, Pennsylvania? That is a different place with its own rules. See our Delaware County, PA guide.

Kent County: January 31

Kent County says appeals of the annual assessments must be received in the Assessment Office by 5:00 pm on January 31, or the last day of January if the 31st falls on a weekend. A postmark is not accepted. All appeals must be in writing, and the form is available from the Assessment Office or the county website. Kent County Assessment FAQs

• An appeal made by the deadline affects taxes for the next tax year, which begins June 1.
• Appeals of a supplemental (quarterly) assessment increase must be filed within 30 days of notification of the increase.
• Kent values are as of the last reassessment, July 1, 2023, and a sale does not by itself trigger a new assessment.
• The county says appeal deadlines may change in reassessment years.

Sussex County: March 15

Sussex County completed a court-ordered reassessment, with values set at projected fair market value as of July 1, 2023. For the 2026 cycle, applications to the Board of Assessment Review were due by March 15, filed through the Board of Assessment Review link on the county's reassessment page, with hearings running as needed through May 31, 2026. Sussex County reassessment page · Sussex County news release

New Castle County: Board of Assessment Review

The New Castle County Board of Assessment Review hears appeals from any owner who alleges the property has been improperly assessed, and orders a reduction when it finds the assessment is greater than it should be. The legal authority is 9 Del. C. 1371A. New Castle County BOAR

The Board's rules (the copy we read was revised March 14, 2025) set these terms:

• File one form per tax parcel, by email to BOARAppeals@newcastlede.gov or in person at the Assessment Division, 87 Reads Way, New Castle, by 4:00 pm on the deadline.
• A form counts as late if it is not received by the deadline, regardless of any postmark. A late form waits for the next annual appeal period.
• You carry the burden. The rules say the assessment is presumed correct and you must show competent evidence that it is wrong.
• A Board decision can be appealed to Superior Court within 30 days of the postmark date of the written decision. Superior Court review is based on the record before the Board. BOAR Rules of Procedure

The annual filing deadline has been extended by ordinance in some years (the rules reference a March 31, 2025 deadline), so confirm the current date on the county's BOAR page before you file.

What Evidence Works

New Castle's rules call for competent evidence that the property is substantially overvalued, so build the case with comparable sales and errors in the property record. Kent notes that Delaware law places the burden of assuring the accuracy of assessment information on the property owner, and that an assessment error found after the appeal period would not normally produce a refund. Kent County Assessment FAQs

Where Grove Hopper Fits

Grove Hopper is a research tool. We look at your property, flag whether it looks over-assessed and prepare your appeal documents. You review, sign and file them yourself with your county. We are not attorneys, accountants or a tax firm. The free check is at the top of this page.