New Castle Property Tax: Rates, BOAR Appeals & Exemptions (2026)

For New Castle County homeowners, the 2026 annual assessment appeal deadline was March 14, 2026; as of September 1, 2026, the next annual appeal window is January 1–March 14, 2027. File with the Board of Assessment Review of New Castle County (BOAR) online through SmartFile, by email to BOARappeals@newcastlede.gov, or by mail/hand delivery to Office of Finance, Assessment Division, New Castle County Government Center, 87 Reads Way, New Castle, DE 19720. Appeals are free.

How assessments work in New Castle County

New Castle County is now on a new assessment base year. The county says all taxable property is assessed at 100% of fair market value as of July 1, 2024. That value is used for the county property tax bill and also for the school district tax bill collected by the county. Delaware law now requires countywide reassessment at least once every five years, so the post-1983 era is over.

The big practical point: your appeal is not about whether your tax bill feels too high. It is about whether New Castle County’s value for your parcel is too high as of July 1, 2024. The county’s residential appeal form repeats that standard and asks you to state what you believe the July 1, 2024 fair market value should be.

For 2026 billing, New Castle County also had an unusual timing issue. The county announced that FY27 bills, covering July 2026–June 2027, will be mailed in November and are due December 31, 2026; FY27 county and school tax rates were expected to be posted on or after October 22, 2026. For a concrete savings example today, the most recent official rate sheet available is the revised 2025–2026 residential/nonresidential table.

Whether you should appeal

Appeal if you can prove a lower fair market value, not just a lower neighbor assessment. BOAR rules and the county guide are explicit: assessed values of other properties and taxes paid by other owners are not competent evidence of overvaluation.

For most homeowners, the strongest package is:

• Closed comparable sales near your home that occurred between January 1, 2022 and June 30, 2024.
• Similar homes: same neighborhood or market area, similar size, lot, age, condition, beds/baths, basement, garage, quality, and style.
• Up to six comparable sales listed on the appeal form. If you want to discuss a sale at the hearing, it must be on the form or attached to it.
• Photos and documents showing condition problems: unfinished areas counted as finished, storm damage, obsolete systems, foundation issues, incorrect square footage, wrong bedroom/bath count, or other physical errors.
• An appraisal only if it is useful enough to justify the cost. For residential appeals, New Castle County says an appraiser is not required, but if you submit an appraisal, it must be by a Delaware-licensed appraiser and must value the property as of July 1, 2024, or be dated after July 1, 2023 under the county guide.

Do not rely only on Zillow/Redfin estimates, active listings, foreclosure/short sale prices, sheriff sales, family transfers, nominal deed values, or “my neighbor’s assessment is lower.” Active listings may support the story, but New Castle says they cannot be your only direct evidence.

No official success rate or median reduction is published in a clean homeowner-friendly table. What the county has published is volume: it reported managing more than 5,300 appeals from the 2025 reassessment and receiving more than 1,500 new appeals for 2026, compared with an average of 64 appeals per year before reassessment. So assume the process is real, but evidence-driven and slow.

Step-by-step how to file

1. Find your parcel number. Use New Castle County Parcel Search and pull the parcel details. Check the assessed land, building, and total value, plus the physical characteristics.

2. Choose the right form. For a typical owner-occupied house, use Residential Assessment Appeal Form. Other official BOAR forms include Nonresidential Assessment Appeal Form, Assessment Appeal Form — Removal of Farmland Assessment, and Appeal of Exemption Removal or Denial.

3. Put a value number on the form. Do not just say “too high.” The residential form asks what you consider the property’s fair market value to have been on July 1, 2024.

4. Attach your proof. List up to six closed comparable sales, with parcel number, owner, address, sale date, sale price, and property characteristics. Add photos and a short written explanation if the county’s record has condition or data errors.

5. File by the deadline. Delaware’s annual rule is effectively “before March 15,” and New Castle County’s current BOAR page states that the 2027 annual appeal window is January 1, 2027 through March 14, 2027. For 2026, the county’s formal appeal guide gave March 14, 2026 at 11:59 p.m. as the deadline for electronic submissions and said paper applications had to be received, not merely postmarked, by March 14, 2026.

6. Use one of the official filing methods.

• Online: New Castle County SmartFile appeal portal.
• Email: BOARappeals@newcastlede.gov.
• Mail or delivery: Office of Finance, Assessment Division, New Castle County Government Center, 87 Reads Way, New Castle, DE 19720.
• In person: same Government Center address; Assessment staff hours are listed as Monday–Friday, 8 a.m.–4 p.m.

There is no filing fee for an annual assessment appeal. File a separate form for each parcel.

What happens after

First, the Assessment Office reviews what you submitted. Four outcomes are common. It may agree with your requested value and close the appeal. It may call or write with a compromise value and ask you to sign a stipulation. It may send a deficiency notice if your proof is incomplete; the county guide says you get 10 days to cure. Or it may schedule a hearing if Assessment believes the county value is correct.

The hearing authority is the Board of Assessment Review of New Castle County, commonly BOAR. BOAR can hear cases itself, in panels, or through referees. Hearings are generally during the day and usually at the Government Center. If your residential appeal does not include appraiser testimony, each side is generally limited to 15 minutes.

A referee hearing can be partly non-oral for the homeowner: if your appeal is scheduled before a referee, the rules say you are not required to attend, and the referee can make a recommendation based on your form and Assessment’s evidence. If your case is scheduled directly before the Board without a referee or panel recommendation, you must appear or the appeal can be considered abandoned and denied.

After a referee or panel hearing, the recommendation is mailed to you and later goes to the full Board for a final decision, with no new testimony or evidence at that later Board step. After final BOAR action, you receive a written ruling. A BOAR decision can be appealed to Delaware Superior Court within 30 days of the postmark date of the written decision, but that appeal is based on the BOAR record; ordinarily, you do not get to introduce a brand-new case.

Local tips

Use the rate table when estimating savings. Suppose a homeowner in an unincorporated Red Clay area (TRS2) reduces an assessment from $425,000 to $390,000. The reduction is $35,000. Using the revised 2025–2026 comprehensive residential TRS2 rate of 0.79188 per $100, estimated annual savings are $35,000 ÷ 100 × 0.79188 = $277.16 before any local light tax, stormwater/maintenance items, or later FY27 rate changes. Of that, the unincorporated county-only residential rate of 0.1575 per $100 represents $55.13; the rest is mainly school, vo-tech, and crossing guard tax.

Fix factual errors even if you missed the appeal deadline. New Castle County says physical-characteristic errors such as square footage, bedrooms, acreage, or condition can be corrected at any time by contacting Assessment or using the online correction process. That is different from a formal value appeal.

Check exemptions separately from appeals. New Castle County does not have a generic “homestead exemption” under that name for every owner-occupied home, but it does have important relief programs. The 2026 over-65 county exemption can reduce assessed value by up to $173,000 for qualifying homeowners, with a June 1, 2026 application deadline, income and residency rules, and a $676,000 assessed-value cap. The disability exemption can also reduce assessed value by up to $173,000, with possible additional amounts up to a $427,000 maximum in certain cases. Delaware’s senior school property tax credit is separate: age-65 homeowners may receive 50% off regular school property taxes, capped at $500, with an April 30 application deadline. Disabled veterans approved for the state disabled veteran school tax credit may also receive a full New Castle County property tax exemption, though local light/stormwater items may remain.

New Castle County Property Tax Rate

FY2027 county real-property rates effective July 1, 2026: residential General Operating rate is 5.39 cents per $100 of assessed value; non-residential General Operating rate is 8.15 cents per $100. For unincorporated residential property, the ordinance also levies a Local Service Function rate of 13.07 cents per $100; school, municipal, light-district, and crossing-guard charges are separate/variable.

Source: https://www.newcastlede.gov/DocumentCenter/View/64273/O26-034-FY2027-Annual-Revenue-Ordinance

When Are Property Taxes Due in New Castle County?

FY27 property tax bills for 7/2026–6/2027 are due December 31, 2026; New Castle County says bills will be mailed in November 2026.

This is not the same as the assessment appeal deadline above. The appeal deadline is your window to contest your assessed value; the payment due date is when the resulting tax bill must be paid. Missing one does not affect the other, but missing either has real consequences — one forfeits your right to appeal for the year, the other can trigger penalties and interest.

Source: https://www.newcastlede.gov/232/Tax-Information-Forms

Property Tax Exemptions in New Castle County

• New Castle County Over-65 / Elderly Property Tax Exemption — Applicants age 65 or older before July 1, 2026 whose dwelling is the applicant’s or spouse’s principal residence; July 1, 2024 assessed value does not exceed $676,000; income does not exceed $65,000 per year for the applicant or married spouses combined, excluding Social Security and Tier 1 Railroad Retirement benefits; Delaware legal domicile for 10 consecutive years before July 1, 2026; and taxes/sewer charges are paid or in an approved current payment plan.. Maximum county exemption is $173,000 subtracted from assessed value for county tax purposes. The same form also describes a school-district elderly exemption up to $173,000 of assessed value for applicants meeting separate school-tax income limits; residents with assessed value over $676,000 and income not over $3,000 may qualify for a $5,000 State senior property tax exemption. Yes, one-time application; no reapplication if already approved and the same property remains the applicant’s/spouse’s principal residence. New application required after transfer to a new principal residence. Apply by 2026-06-01. (Source: https://www.newcastlede.gov/DocumentCenter/View/62375/Elderly-Exemption---2026-01-06)
• New Castle County Disability Property Tax Exemption — Applicants who became disabled before July 1, 2026, use the property as the applicant’s or spouse’s principal residence, meet the $65,000 annual income limit for the applicant or married spouses combined, have been legally domiciled in Delaware for 10 consecutive years before July 1, 2026, and have taxes/sewer charges paid or in an approved current payment plan. The 10-year domicile requirement is waived for certain totally and permanently disabled service-connected veterans with honorable discharge and documentation.. Maximum county exemption is $173,000 of assessed value; additional county exemptions up to $227,000 may apply for qualifying loss/loss of use of extremities requiring special fixtures, and up to $27,000 may apply for disability incurred in U.S. armed-services service. The form states a maximum of $427,000 of assessed value as to county taxes, with similar school-tax amounts where school-tax criteria are met. Yes, one-time application; no reapplication if already approved and the same property remains the applicant’s/spouse’s principal residence. New application required after transfer to a new principal residence. Apply by 2026-06-01. (Source: https://www.newcastlede.gov/DocumentCenter/View/62373/Disability-Exemption-Fillable-Form---2026-01-06)
• State of Delaware Senior School Property Tax Credit — Delaware homeowners age 65 or older claiming the credit on regular school property taxes for their primary residence; new applicants who established Delaware domicile on or after January 1, 2018 must have 10 consecutive years of Delaware domicile, while those who established domicile after December 31, 2012 and before January 1, 2018 need 3 consecutive years. Prior property tax bills must be paid in full by the end of each tax year to qualify for the subsequent year.. Credit against regular school property taxes of 50%, up to $500, on a primary residence. Yes, initial application submitted to the county; no annual reapplication once qualified, but a move may require county instructions/new application. Apply by April 30 for the upcoming tax year. (Source: https://finance.delaware.gov/senior-relief/)
• State of Delaware Disabled Veterans School Property Tax Credit — Veterans who receive 100% disability compensation due to service-connected, permanent and total disability based on individual unemployability or a 100% disability rating from the U.S. Department of Veterans Affairs, have held legal domicile in Delaware for the past 3 years, and claim the credit on a primary residence. The taxpayer cannot claim both this credit and the Senior School Property Tax Credit.. Credit against 100% of non-vocational school district property tax on the primary residence. Yes, application submitted to the county; once qualified, no annual reapplication, but a new application is needed for a new principal residence and rating changes must be reported as required. Apply by April 30 for the upcoming tax year. (Source: https://finance.delaware.gov/disabled-veterans/)
• New Castle County full county-tax exemption for qualifying disabled-veteran school-credit recipients — Veterans who qualify for the State of Delaware Disabled Veteran’s School Tax Credit under 14 Del. C. § 1917(d), as administered by the Delaware Division of Revenue and submitted through the Assessment Division.. The county disability-exemption form states that if the applicant qualifies for the State Disabled Veteran’s School Tax Credit, the applicant will automatically receive a full exemption of the total assessed value of the property for county tax purposes, excluding any local light and ditch taxes or stormwater maintenance fee. Yes, separate State Disabled Veteran’s School Tax Credit application submitted to the Assessment Division. Apply by April 30 for the upcoming tax year. (Source: https://www.newcastlede.gov/DocumentCenter/View/62373/Disability-Exemption-Fillable-Form---2026-01-06)
• Line of Duty Death Property Tax Exemption — A surviving spouse of a covered person whose death qualifies as a line-of-duty death under 18 Del. C. §§ 6601–6602 or 10 U.S.C. §§ 1475–1480; the applicant must have been awarded the qualifying benefit after January 1, 2011, own and occupy the residence as principal residence, not have remarried, and have county taxes/sewer charges paid or in an approved current payment plan.. Exemption remains in effect for 10 years so long as the surviving spouse does not remarry, remains titled owner, and maintains the property as principal residence; if the property is co-owned, the exemption applies only to the applicant’s percentage of the property’s total assessment. Yes, initial application with proof of benefit/certification and marriage certificate; no reapplication if approved within the last 10 years and qualifications/property remain unchanged. Apply by 2026-06-01. (Source: https://www.newcastlede.gov/DocumentCenter/View/64081/LODD-Exemption--Form---51326-Fillable)

How to Look Up Your Property Record in New Castle County

You can look up your property's official record at https://www3.newcastlede.gov/parcel/search/. The official Parcel Search lets users search by parcel number, street address, deed book/page, subdivision, or lot; New Castle County’s Recorder of Deeds page says it provides owner, tax information, and sales history.