Delaware homeowners pay a median of $1,768 a year in property tax, an effective rate of 0.50%, the 43rd highest of the 51 states we cover. The deadline to appeal: Jan (Kent), Mar 14–15 (NCC, Sussex). Here is who sets your value, how to challenge it and what evidence works.
Opens soonAll 2026 deadlines have passed (Kent January 30, New Castle March 14, Sussex March 15). Next deadlines: Kent by 5 p.m. Friday, January 29, 2027 (Kent's FAQ says January 31; the earlier date is the safe one); New Castle before March 15, 2027; Sussex's filing period usually opens in mid-January and closes March 15 (2027 dates were not posted on the Sussex board page when checked).
Each county has its own fixed yearly deadline, and the filing must be received, not just postmarked. New Castle County: file before March 15 (in 2026 the county set the deadline as March 14, 2026). Kent County: the appeal must reach the Assessment Office by 5:00 p.m. on the last working day of January (January 30, 2026; next is Friday, January 29, 2027). Kent's FAQ and credits page say January 31, so use the earlier date; the deadline can change in reassessment years. Sussex County: the 2026 filing period ran January 12 to 4:30 p.m. on March 15, 2026; postmarks were not accepted. An appeal filed in a given year affects the tax bill for the tax year that starts that summer (June 1 in Kent). In Kent, if the county raises your value mid-year with a supplemental (quarterly) assessment, you have 30 days from that notice to appeal.
In a reassessment year every owner gets a notice of the new value. In other years there is no annual notice: the county publishes a newspaper notice saying where to look up assessments and when to appeal. If the county raises your value outside a general reassessment (for example, after new construction), it must send you written notice at least 10 days before the change.
Where you file depends on your county. Pick yours for the office contacts, local tax figures and a step-by-step guide.
Enter the market value on your assessment notice and what you think the home would really sell for. We estimate the yearly saving if the board agrees with you.
Some states cap how fast the taxable value of a home can rise (California, Florida, Michigan and Texas homesteads, for example). If your taxable value is already held below market value by a cap, a lower market value may not lower this year's bill.
Each of Delaware's three counties values homes: the New Castle County Office of Finance (Assessment Division), the Kent County Department of Finance (Assessment Division) and the Sussex County Assessment Department. Appeals go to each county's Board of Assessment Review. There is no state assessor. Homes are assessed at 100% of fair market value as of the base date of the county's latest reassessment, not today's value. After the court-ordered statewide reassessment, the base dates are July 1, 2023 in Kent and Sussex and mid-2024 in New Castle (2024 base year). Your value stays the same each year unless the county reassesses, you change the property (for example, an addition), or the county fixes an error. All three counties finished general reassessments for the 2025 tax bills, the first in decades (Kent's previous base year was 1987, Sussex's 1974). State law now requires every county to reassess all property at least once every 5 years, counted from the date the county certifies the reassessment roll (9 Del. C. § 8306).
In Kent and Sussex, an assessor reviews your appeal before any hearing. If you and the assessor agree on a value, you sign a stipulation (Kent) or accept the change by email (Sussex), and the Board approves it; if not, the case goes to a hearing. You can also call the assessment office to check your property record (square footage, basement, bathrooms) and get errors fixed; Kent will give you a copy of your property record card on request, at least 3 days before a hearing.
What works in Delaware: At least 3 arm's-length sales of similar homes near the base date (Sussex and Kent: sales from January 1, 2021 to June 30, 2023; New Castle: roughly 2022 to mid-2024); An appraisal valuing the home as of the base date. New Castle requires a Delaware-licensed appraiser; in Kent and Sussex the appraiser must attend the hearing to testify; Your own purchase price and date, if you bought in an open-market sale near the base date; Photos showing condition problems; Corrections to the property record (square footage, basement finish, bathrooms, outbuildings).
File one written appeal form per parcel with your county by its deadline, with all your evidence attached. New Castle: residential appeal form by mail or in person at the Government Center, 87 Reads Way, New Castle, or online through the county's SmartFile portal; hearings are short (about 15 minutes) and usually held by a referee or a panel who recommend a value to the Board. Kent: deliver or mail the form so it arrives at 555 Bay Road, Dover by the deadline, and serve a copy on the Assessment Office (the form has a certificate of service); in reassessment years a hearing officer hears the case first, then the 7-member Board decides. Sussex: email the form to [email protected], mail it to PO Box 589, Georgetown, or deliver it to 2 The Circle; list at least 3 comparable sales (up to 6). Hearings run March through May (Kent and Sussex) and later in New Castle. The Board must mail its written decision within 30 days of deciding. Cost: No filing fee appears on the Kent or Sussex forms. New Castle calls the process free (Town Square Delaware, Feb. 2026).
You must prove your home's assessment is higher than its fair market value on the county's base date, using evidence filed with your appeal. In Superior Court the Board's decision is presumed correct: you must show the Board acted contrary to law, fraudulently, arbitrarily or capriciously, and your evidence must be sufficient to show a substantial overvaluation (9 Del. C. § 8312(c); the 'substantial overvaluation' test comes from case law, Fitzsimmons v. McCorkle (Del. 1965), quoted in Burroughs v. Kent County Assessment Office (Del. Super. May 15, 2025)).
Within 30 days (by postmark) after you receive the Board's written decision. File an appeal in the Superior Court for your county. The Board sends the court its hearing record within 20 days, and the court mostly reviews that record, though it may allow new evidence. The court can affirm, reverse, change or send back the decision; its decision is final. Court filing fees apply; check with the Superior Court Prothonotary.
The Board orders the county to lower your assessment, and the new value is used for that tax year and later years until the next reassessment or a change to the property. If you already paid at the higher value, the county refunds an overpayment of $50 or more (smaller amounts may be credited). Kent's FAQ says an error found after the appeal period would not normally produce a refund, so appeal on time.
Delaware appeals are decided on your home's market value on the base date. Kent's list of inadmissible evidence excludes assessed values of properties that are not comparable, so comparisons only help with truly similar homes. Sussex refuses neighbors' assessed values as evidence, so back any unfairness claim with sales of similar homes. This works only in limited cases. Run the numbers with our unequal assessment calculator.
Most wins start with a mistake in the assessor's record of your home. Check it line by line.
Record card checklistAn exemption is separate from an appeal: you apply once and it cuts your taxable value every year. Check you have every one you qualify for.
Homeowners 65 and older get a credit of 50% of school property taxes on their main home, up to $500. People who moved to Delaware on or after January 1, 2018 must have lived in the state 10 years first. Apply to your county by April 30.
For owners 65 and older: exempts up to $173,000 of assessed value from county property tax if income is no more than $50,000 (single) or $65,000 (couple). A separate school-tax elderly exemption uses the same $173,000 amount but much lower income limits ($15,000 single, $19,000 couple).
For owners 65 by May 31 or 100% disabled, with 5 years of Delaware residency and income up to $18,000 (single) or $24,750 (couple), not counting Social Security. Reapply every year by April 30.
For owners 65 by June 30 or totally disabled, 5-year Sussex residents, with non-Social Security income up to $6,000 (single) or $7,500 (married). Exempts up to $229,000 of assessed value. File January 1 to April 30.
You can file and argue your own appeal; you do not need a lawyer. Kent allows a representative with your written authorization that discloses any personal interest and any contingency fee (attorneys need not disclose their fee); Kent's residential instruction sheet (linked under forms) says the petitioner must attend or be represented by a Delaware attorney. In Sussex you may skip the hearing and have the Board decide on your application. An appraiser's report counts only if the appraiser testifies.
Fill in your details and download a written appeal statement as a PDF or Word file. Most boards also require their own appeal form: file the form and attach this letter and your evidence to it.
Tax Appeal Map is a free information site, not a law firm or appraiser. The letter is a template, not legal advice.
Each county has its own fixed yearly deadline, and the filing must be received, not just postmarked. New Castle County: file before March 15 (in 2026 the county set the deadline as March 14, 2026). Kent County: the appeal must reach the Assessment Office by 5:00 p.m. on the last working day of January (January 30, 2026; next is Friday, January 29, 2027). Kent's FAQ and credits page say January 31, so use the earlier date; the deadline can change in reassessment years. Sussex County: the 2026 filing period ran January 12 to 4:30 p.m. on March 15, 2026; postmarks were not accepted. An appeal filed in a given year affects the tax bill for the tax year that starts that summer (June 1 in Kent). In Kent, if the county raises your value mid-year with a supplemental (quarterly) assessment, you have 30 days from that notice to appeal.
With the County Board of Assessment Review appeal. File one written appeal form per parcel with your county by its deadline, with all your evidence attached. New Castle: residential appeal form by mail or in person at the Government Center, 87 Reads Way, New Castle, or online through the county's SmartFile portal; hearings are short (about 15 minutes) and usually held by a referee or a panel who recommend a value to the Board. Kent: deliver or mail the form so it arrives at 555 Bay Road, Dover by the deadline, and serve a copy on the Assessment Office (the form has a certificate of service); in reassessment years a hearing officer hears the case first, then the 7-member Board decides. Sussex: email the form to [email protected], mail it to PO Box 589, Georgetown, or deliver it to 2 The Circle; list at least 3 comparable sales (up to 6). Hearings run March through May (Kent and Sussex) and later in New Castle. The Board must mail its written decision within 30 days of deciding.
No filing fee appears on the Kent or Sussex forms. New Castle calls the process free (Town Square Delaware, Feb. 2026).
In Kent and Sussex, an assessor reviews your appeal before any hearing. If you and the assessor agree on a value, you sign a stipulation (Kent) or accept the change by email (Sussex), and the Board approves it; if not, the case goes to a hearing. You can also call the assessment office to check your property record (square footage, basement, bathrooms) and get errors fixed; Kent will give you a copy of your property record card on request, at least 3 days before a hearing.
You can appeal to the Delaware Superior Court (in your county). Within 30 days (by postmark) after you receive the Board's written decision. File an appeal in the Superior Court for your county. The Board sends the court its hearing record within 20 days, and the court mostly reviews that record, though it may allow new evidence. The court can affirm, reverse, change or send back the decision; its decision is final. Court filing fees apply; check with the Superior Court Prothonotary.
The Board orders the county to lower your assessment, and the new value is used for that tax year and later years until the next reassessment or a change to the property. If you already paid at the higher value, the county refunds an overpayment of $50 or more (smaller amounts may be credited). Kent's FAQ says an error found after the appeal period would not normally produce a refund, so appeal on time.
Checked 2026-10 against official Delaware sources. Local deadlines and fees can differ; confirm with your assessor or board.