Verified July 2026 · By Oleg Kachko · Reviewed for accuracy against primary state and county sources
New Castle County property tax costs the typical homeowner about $2,499 a year, on a median home value of $352,200 – an effective rate of about 0.72%. That is below the national average annual bill of $4,271. This page shows you where that number comes from, who actually sets it, the deadline to challenge it, and the exemptions you may be leaving on the table.
New Castle County property tax at a Glance
- Effective property tax rate: 0.72%
- Median annual bill: $2,499
- Median home value: $352,200
- Who assesses your home: New Castle County Assessor
- Appeal deadline: Around mid-March
On this page
New Castle County property tax: the real numbers
Property tax is the most local tax there is. Two homes of the same value in different counties – sometimes in different towns of the same county – can carry very different bills, because the rate is the sum of every overlapping district that taxes you: the county, the town or city, the school district, and often fire, library or water districts on top. So the new castle county property tax figure below is an average across the whole county – your own bill depends on which districts you sit inside.
| Figure | New Castle County | National |
|---|---|---|
| Median annual property tax bill | $2,499 | $4,271 |
| Effective property tax rate | 0.72% | about 0.90% |
| Median home value | $352,200 | – |
Source: U.S. Census Bureau American Community Survey (5-year), the same dataset the Tax Foundation uses. The effective rate is total real-estate taxes paid divided by total owner-occupied home value – so it reflects what people actually pay, not the headline millage rate.
Who actually sets your new castle county property tax value
Your assessed value is set by New Castle County Assessor. That office does not set your tax rate – the county board, your city, and your school district each set their own, and your bill is the sum. So the assessor can only be argued with about one thing: what your home is worth. That is exactly what an appeal is.
Worth knowing about New Castle County:
Delaware sets appeal deadlines COUNTY BY COUNTY – New Castle is around mid-March, Kent is March 31, Sussex varies. There is no Delaware-wide date. Confirm yours with the county.
How often your new castle county property tax value is reassessed:
Each county (New Castle, Kent, Sussex) runs its own assessment. After decades without reassessment, all three counties reassessed to current market value in 2024-2025 (by court order); counties will now reassess periodically (Kent again in 2028). There is no state property tax.
How to appeal your new castle county property tax assessment
⚠ The deadline — miss it and you usually wait a full year
Around mid-March
Appeal your assessed value to your county’s Board of Assessment Review – deadlines are set by each county (for example New Castle around mid-March, Kent by March 31; Sussex varies) and the boards hear appeals on a set schedule. Then Superior Court. Confirm your county’s exact filing deadline.
Almost every new castle county property tax appeal comes down to one claim: the assessor thinks my home is worth more than it really is. Everything below is about proving that.
Do this first, before you file anything: ask for your property record card and read it. A surprising share of assessments are simply wrong on the facts – the wrong square footage, a bathroom you do not have, a finished basement that is bare concrete, a garage that was torn down. Factual errors are the easiest appeals to win, because there is nothing to argue about.
Then build the one thing that actually wins appeals: comparable sales. Find three to five homes near you, as similar as you can get on size, age, and condition, that sold recently for less than your assessed value. Not listings – sales. Not Zillow estimates – recorded sales. Boards ignore opinions and respond to comps.
A successful new castle county property tax appeal does not change your tax rate – it lowers the value the rate is applied to, which lowers the bill for as long as the new value stands.
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Appeals are heard by the County Board of Assessment Review (then Superior Court). In most places there is a free, informal step first – a conversation or a paper review with the assessor – and it resolves a large share of cases without a hearing. Take it. It costs you nothing and it is the fastest way to win.
One honest warning: an appeal reviews your value, and a review can go up as well as down. That is uncommon when you bring real comparable sales, and it is exactly why you check your comps before you file.
Where to go: find your office through Delaware Dept of Finance, which lists the assessing office for every county in Delaware.
New Castle County property tax exemptions you may qualify for
This is where most homeowners quietly overpay their new castle county property tax. Exemptions are almost never applied automatically – you have to claim them, and many people simply never do. It is worth ten minutes of your time to check.
HOMESTEAD: No statewide value exemption; relief is via the school-tax credits below and county programs. Confirm with your county assessment office. | SENIOR: 50% of the school tax, up to $500. Local school boards may set the cap below $500. Confirm with your county / school district. | VETERAN: 100% of school district property tax (no $500 cap), plus county/local exemption in many counties – can zero out the bill. Confirm with your county.
| DISABILITY: County-specific (some counties give a partial exemption for low-value owner-occupied homes). Confirm with your county assessment office.
Homestead: Delaware has no statewide homestead value exemption and no state property tax – property tax is county + school + municipal. Homeowner relief comes as the Senior School Property Tax Credit and the Disabled Veterans School Property Tax Credit (below), plus some county-level senior/disabled exemptions. NOTE: all three counties recently completed court-ordered reassessments (their first in decades), so many assessed values changed sharply.
Senior / over-65: Senior School Property Tax Credit – a state credit of 50% of regular (non-vocational) school property tax, up to $500, for owners 65+. NO income limit, but there is a domicile requirement: you must have been a Delaware resident for 10 consecutive years if you established domicile on/after January 1, 2018 (3 years for 2013-2017; grandfathered if before 2013). One-time application, due April 30. Prior-year taxes must be paid in full to keep the credit.
Veteran: Disabled Veterans School Property Tax Credit (HB 214, effective 2022) – a credit of 100% of the non-vocational school district property tax for a veteran with a 100% service-connected permanent & total disability (or 100% individual unemployability) who has held Delaware domicile 3 years. Many counties also fully exempt the county/local school portion for these veterans. Apply with the county by April 30 (cannot combine with the senior credit).
Disability: Totally disabled homeowners may qualify for county-level senior/disabled exemptions (each county sets its own rules and value limits); the state’s headline credits are age- and veteran-based. Check your specific county’s program.
Common questions about new castle county property tax
Why did my new castle county property tax bill go up when I did nothing to the house?
Two different things can raise a bill: your assessed value went up, or a taxing district raised its rate. They are separate, and only the first one can be appealed. Your notice will show which changed.
Is it worth appealing my new castle county property tax?
Ask one question: would a similar home near mine sell for less than the value the assessor has put on mine? If yes, you have a case, it is usually free to file, and in many places the informal review settles it without a hearing.
Do I need to hire someone to appeal?
No. The informal review and the local board are built for ordinary homeowners to use themselves, and there is normally no fee. Appeal services exist and can be worth it for some people, but you are not required to use one and you should never be told you are.
How is my new castle county property tax bill actually calculated?
Your assessed value is multiplied by the combined rate of every district that taxes you, then any exemptions you have claimed are subtracted. That is why two neighbours can pay different amounts on identical homes – one of them claimed an exemption the other never did.
More on Delaware property tax
- Delaware property tax rates — how New Castle County compares with every other county in the state.
- How to win your Delaware property tax appeal — the evidence that works and what to say at the hearing.
- Delaware property tax exemptions — who qualifies, how much each one saves, and how to apply.
- Delaware property tax due dates — when the bill is due and what happens if you are late.
- Property tax by state — every state, side by side.
The bottom line on new castle county property tax
Do two things this week. First, pull your property record card and check the facts – square footage, rooms, condition. Second, check whether you are claiming every exemption you are entitled to, because most people are not. If your new castle county property tax value looks higher than what a similar home nearby would actually sell for, you have grounds to appeal – and the only thing that can stop you is the deadline above.
Where our new castle county property tax figures come from
- U.S. Census Bureau, American Community Survey — the rate, median bill and median value on this page.
- Tax Foundation, Property Taxes by State and County — the same dataset and method.
- Delaware Dept of Finance — the office that can confirm your value, your exemptions and your deadline.
- Delaware Dept of Finance (finance.delaware.gov); Delaware Division of Revenue; New Castle / Kent / Sussex county assessment offices
Informational only. Know Property Tax is not a government agency, not a county assessor, and not a tax-appeal service, and this is not legal, tax, or financial advice. Property tax rates, median bills, exemption amounts, and deadlines change every year, and every property is different. Any figure shown here is illustrative. Confirm your rate, your exemptions, and above all your appeal deadline with the office named on this page before you act.
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- Delaware County Property Tax 2026: Rates, Appeals and Exemptions
- Union County Property Tax 2026: Rates, Appeals and Exemptions
- Jefferson County Property Tax 2026: Rates, Appeals and Exemptions