New Castle County, DE follows the Delaware statutory schedule. This page shows that schedule, the county's own website, and the late penalty — the county can still set its own dates, so confirm before you pay.
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…until annual - kent — June 2, 2027
Instalment
Due date
Notes
Annual - Kent
June 2, 2027
Annual bill in Kent County; penalties start September 30.
Annual - New Castle and Sussex
July 2, 2027
Annual bill in New Castle and Sussex; New Castle penalties start September 1, Sussex penalties September 30.
Statewide schedule — read this before you rely on it
The statute itself sets different dates by county: Kent is due June 1, New Castle and Sussex July 1, with penalties starting September 1 versus September 30. Most counties in this state follow these dates.
After the county penalty date (September 1 in New Castle, September 30 in Kent and Sussex), monthly penalties accrue: 6% plus 1% per month in New Castle and 1.5% per month in Kent and Sussex.
Each county mails a single annual bill, and state law requires the statement within 30 days after taxes become due.
New Castle County at a glance
Population: 578,592 (Census estimate, 2023) — the 1st largest of 3 Delaware counties and county equivalents.
Typical tax bill: $2,369 a year (median for owner-occupied homes, ACS 2022 5-year estimate) — the Delaware median is $1,674.
Land area: 426.3 sq mi, about 1,357.1 people per sq mi.
On a $400,000 purchase in New Castle County, DE, property tax comes to about $2,964 a year — roughly $247 a month — at this county's effective rate of 0.74%.
$
Effective rate 0.74% = this county's median owner-occupied tax bill ($2,369, ACS 2022 5-year estimate) divided by the typical home value at the time ($319,751, Zillow, 2022-12-31). Exemptions the seller holds — homestead, senior, veteran — usually do not transfer with the deed, so a new purchase can run above this figure. The county assessor sets the assessed value; this is an estimate, not a quote.
How to pay New Castle County property tax
County website:www.newcastlede.gov — start here for the treasurer or tax collector page.
By post: mail to the county treasurer; the postmark usually counts, not the arrival date.
In person: the treasurer's office, with your bill or parcel number.
Escrow: if your mortgage escrows taxes, the servicer pays — you still owe any shortfall.
Is this county verified?
Not yet. New Castle County is on the queue: we publish a county's own published dates once they have been checked against the county website. Ask for it and it moves up. Until then, the Delaware statutory schedule above is the reliable starting point.
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StacyApproved is an independent reference and is not a government agency. Deadlines change and exceptions apply — always confirm with your county treasurer using the official link on this page. Nothing here is tax, legal or financial advice.