How do I appeal my property tax assessment?

County Board of Assessment Review (county level) / Delaware Superior Court (judicial appeal)

Step by Step

How to do it

Review your property assessment notice when received (New Castle and Sussex County: mailed November 2024 for 2025 tax year; Kent County: mailed 2023 for 2024 tax year)
Contact the County Assessor informally first - most counties offered informal review periods during the reassessment process; some still allow informal contact before formal filing
Obtain the Board of Assessment Review appeal application from your county assessor's office or website
File written appeal with the County Board of Assessment Review by the deadline:
- New Castle County: approximately March 14-31 (varies; 2025 deadline was March 31); verify current year deadline
- Kent County: approximately March 15 each year; verify current year deadline
- Sussex County: verify with county - special extended appeal windows were created during reassessment
Gather supporting evidence: comparable sales data as of the reassessment date, recent independent appraisal, photos of property condition, factual errors in property record
Attend your Board of Assessment Review hearing (typically March-April); present evidence concisely (typically 5-15 minutes)
Receive the Board's written decision
If unsatisfied: appeal to Delaware Superior Court within 30 days of the Board's decision

Details

What you need to know

Required Docs

Completed Board of Assessment Review appeal application (county-specific)
Supporting evidence: comparable sales, independent appraisal, photos, factual documentation
Property parcel number and assessment notice

Fee

No fee for Board of Assessment Review appeal; Superior Court appeal involves filing fees and typically requires a certified real estate appraisal APPEAL DEADLINE: Approximately March 14-31 for New Castle County; approximately March 15 for Kent County; verify annually HEARING: Typically March-April each year SUPERIOR COURT: Must file within 30 days of Board's written decision ONLINE OPTION: Some counties accept online or email filing of appeal forms - check your county assessor's website WHERE TO GO: County Board of Assessment Review (forms from County Assessor); Delaware Superior Court (judicial appeal)

Online Option

Some counties accept online or email filing of appeal forms - check your county assessor's website

Where to Go

County Board of Assessment Review (forms from County Assessor); Delaware Superior Court (judicial appeal)

County-specific variations apply

Each of Delaware's three counties has its own Board of Assessment Review with different deadlines, procedures, and forms. Deadlines shifted significantly during the 2024-2025 reassessment cycle - ALWAYS verify the current year's deadline directly with your county assessor before assuming a prior year's date applies. New Castle County extended deadlines and created additional appeal support during the 2025 reassessment. Sussex County's 2025 values were finalized June 30, 2025.

Delaware Notes

Important state-specific details

Delaware's reassessment shock was severe - some properties saw 300-500% increases in assessed values (though rate adjustments moderated actual tax bill increases).
Evidence should be based on comparable sales as of the assessment date (July 1, 2024 for New Castle and Sussex 2025 reassessment) - not current market conditions.
Delaware has NO assessment caps or homestead freeze programs comparable to other states - property owners are uniquely exposed to assessment changes.
Senior School Tax Credit ($500): separate from assessment appeal; apply to Division of Revenue; reduces school taxes for homeowners 65+.
HB 62 (2023): requires all three Delaware counties to reassess every 5 years going forward - the era of 40-year gaps is over.

Official Source

State office contact

State Office

County Assessor's Office (varies by county); Delaware Superior Court - courts.delaware.gov | (302) 255-0800