Why Is Your Delaware Property Tax Increasing?

If you are wondering why your Delaware property tax is increasing, the short answer is that Kent, New Castle, and Sussex counties just finished their first property reassessments in more than 40 years. Values that had been frozen since the 1970s and 1980s were replaced with current market values, and even though tax rates were cut to offset the jump, your bill still rises if your home gained more value than the county average.

What the Reassessment Changed

For decades, Delaware taxed homes using a single “base year” value from the 1970s or 1980s. A 2020 Court of Chancery ruling found that approach unconstitutional, and each county had to redo its numbers. Kent County’s new values took effect for tax year 2024. New Castle County and Sussex County went live for tax year 2025.¹

The practical result is a much larger assessed value on your notice. A home carried at $85,000 under the old system might now show $350,000 or more. That new number is only half of the calculation, though. The tax rate applied against it also changed.

Why Rates Dropped But Your Bill Still Went Up

Delaware law blocks counties, school districts, and municipalities from collecting a windfall from reassessment. Each taxing authority has to compute a “rolled-back rate,” a new lower rate designed to raise roughly the same total revenue as the prior year.² If total assessed value in a county doubles, the rate gets cut roughly in half.

There are caps on how much any one jurisdiction can exceed that rolled-back figure:

Counties cannot collect more than 15% above the prior year’s property tax revenue.²
School districts are limited to 10% above the prior year unless voters approve more at a referendum.³
Municipalities must compute and publicly disclose their rolled-back rate and any increase above it, though the statute does not set a hard numeric cap.⁴

Counties also have to advertise any adopted increase in a newspaper within 15 days of the vote.² So you can see on paper whether your county, school district, or town chose to collect extra on top of the rolled-back rate.

Those protections control total collections across every property. They do not promise that your individual bill will stay flat. The bill depends on how your property’s value changed relative to everyone else’s. If your county’s total value doubled but your home’s value tripled, you now owe a bigger share of the pie. Rate down, assessed value up by much more, net result higher.

Who Pays More and Who Pays Less

Owners whose property appreciated faster than the county average end up with higher bills. Owners whose property grew more slowly than the average often see flat or lower bills, because their share of the total tax burden actually shrank. That redistribution is what the uniformity clause was meant to produce: similar properties contributing similar amounts, regardless of when they were last assessed.

The sharpest increases tend to show up on waterfront properties, homes near commercial development corridors, and neighborhoods that gentrified since the old base years were set. Rural properties with modest appreciation often come out better under the new system.

How to Appeal If the New Value Looks Wrong

You can challenge your new assessed value, but each county runs its own appeal process with its own deadline. Missing the deadline forfeits your right to challenge for that tax year, so check your notice as soon as it arrives.

Kent County: annual appeal applications are due by the last working day in January. Supplemental bills have separate deadlines.⁵
Sussex County: for 2026, the filing window opens January 12 and applications must be received by 4:30 p.m. on March 15. Postmarks are not accepted. Hearings run March through May.⁶
New Castle County: the Board of Assessment Review handles appeals; check the county’s reassessment page for the current filing window.¹

The question before the board is whether the assessed value reflects what your property would actually sell for. The strongest evidence is recent sale prices of comparable homes nearby with similar square footage, lot size, and condition. A professional appraisal also carries weight, though it typically costs several hundred dollars. Complaints about tax rates or government spending carry no weight at an assessment hearing.

In Sussex County, an assessor first reviews your application and supporting documents. If the assessor proposes a revised value, you can accept it or request a formal hearing before the Board of Assessment Review.⁶ Thorough documentation at that first stage resolves many cases without a hearing. If the board rules against you, you have 30 days to appeal to Superior Court.⁵

Credits and Exemptions That Can Lower the Bill

Senior School Property Tax Credit

Homeowners age 65 or older can claim a credit worth 50% of their regular school property taxes, up to $500 per year, on a primary residence.⁷ Residency rules depend on when you moved to Delaware:

Moved between January 1, 2013 and December 31, 2017: at least 3 consecutive years of Delaware residency before applying.
Moved on or after January 1, 2018: at least 10 consecutive years of residency before applying.⁸

The statewide deadline is April 30, and the credit cannot be applied retroactively.⁸ You also must have paid the prior year’s property tax bill in full to remain eligible.⁷ The 10-year rule catches many recent arrivals off guard: someone who retired to Delaware in 2019 will not qualify until 2029 at the earliest.

Senior and Disability Assessment Exemptions

Separate from the school tax credit, counties offer reductions in taxable assessed value for residents 65 or older or 100% disabled with documentation. Kent County, for example, requires at least five years of Delaware residency, ownership as a primary residence, and adjusted gross income below $18,000 for a single applicant or $24,750 for a couple. Social Security and disability-related income are excluded from that calculation.⁹ These exemptions must be renewed each year by April 30, with all county taxes paid in full by the application deadline.

Disabled Veterans School Tax Credit

Veterans with a documented VA disability rating can apply for a separate school property tax credit. You will need a Delaware driver’s license or state ID, your VA disability rating documentation, and a copy of your Social Security card.¹⁰ Forms are available through county government websites and local assessment offices.

Paying the Bigger Bill

Higher assessments make the payment deadlines more consequential than they used to be. Due dates and penalties vary:

Kent County: taxes due June 1. Penalties of 1.5% per month start after September 30.
New Castle County: taxes due July 1. After September 1, a 6% penalty is added to the current charge, plus 1% of the unpaid balance on the first of every subsequent month.
Sussex County: taxes due July 1. Penalties of 1.5% per month start after September 30.¹¹

Every county must offer a payment plan for residential taxpayers. If you enter a plan and make the installments on time, the county waives all penalties, interest, and late fees. The plan has to allow at least three equal installments for school taxes.¹¹ If the new bill strains your budget, call the county tax office before the penalty date, not after.

Watch Your Mortgage Escrow

If your mortgage includes escrow for taxes and insurance, a bigger property tax bill will eventually push your monthly payment up. Your lender runs an annual escrow analysis comparing collections against disbursements. A reassessment-driven tax increase shows up as a shortage, and the servicer raises your monthly payment to close the gap.

Federal rules under the Real Estate Settlement Procedures Act cap the servicer’s extra cushion at one-sixth of your estimated annual escrow disbursements. Your servicer must send you an annual escrow statement within 30 days of the end of the computation year showing the new balance, projected payments, and any shortage or surplus.¹² Most servicers let you pay a shortage either as a lump sum or spread across 12 monthly payments. Read this notice carefully in the year after your county’s reassessment, because the monthly increase can run into the hundreds depending on how much your assessed value jumped.

What It Means for Your Federal Deduction

Delaware property taxes are deductible on your federal return if you itemize.¹³ The federal state and local tax deduction is capped. For 2026, the SALT cap is $40,400 for most filers and $20,200 for married filing separately.¹⁴ That cap covers all state and local taxes combined: property taxes plus either state income tax or state sales tax.

For most Delaware homeowners, the reassessment alone will not push total SALT over $40,400. If you live in a high-value area and also pay state income tax, the cap could limit how much of the increase you can deduct. If your total stays under the cap, the larger bill at least produces a proportionally larger federal deduction, which absorbs part of the hit.

1
New Castle County, DE – Official Website. Reassessment Project Information
2
Delaware Code Online. Delaware Code Title 9 – County Tax Levy
3
Delaware Code Online. Delaware Code Title 14 – School District Taxation
4
Delaware Code Online. Delaware Code Title 22 – Assessments for Municipal Taxation
5
Kent County. Property Assessment Appeal Procedures
6
Sussex County Government. Guidelines for Filing an Appeal
7
State of Delaware. Senior School Property Tax Relief
8
State of Delaware. Application for Senior School Property Tax Credit
9
Kent County. Credits and Exemptions for Seniors, Disabled and Veterans
10
Department of Finance – State of Delaware. Disabled Veterans School Tax Credit
11
Delaware Code Online. Delaware Code Title 9 – County Taxes
12
Consumer Financial Protection Bureau. Escrow Accounts
13
Internal Revenue Service. New and Enhanced Deductions for Individuals
14
Office of the Law Revision Counsel. 26 USC 164 – Taxes