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%.
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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.
If you pay late
Unpaid bills incur a 6% penalty on property line items and 1% on school line items in the first delinquent month, then 1% a month on all items.
Fiscal year July 1 to June 30; FY27 bills are mailed in November. If a due date lands on a weekend or public holiday, most counties move it to the next business day — check the county's own notice before relying on the shift.
How to pay
Online: through ipn.paymentus.com — the only portal this county operates.
By post: mail a cheque to the treasurer's office; the postmark date usually counts, not the arrival date.
In person: the treasurer's office during business hours; bring your bill or parcel number.
Mortgage escrow: if your taxes are escrowed, the servicer pays — you still owe the difference if your escrow is short.
Common questions
When are property taxes due in New Castle County, DE?
Full year: December 31, 2026.
What happens if I pay late in New Castle County?
Unpaid bills incur a 6% penalty on property line items and 1% on school line items in the first delinquent month, then 1% a month on all items.
How do I pay New Castle County property tax?
Pay online through ipn.paymentus.com, the county's own payment portal, or by post or in person at the treasurer's office.
Is the New Castle County deadline the same every year?
Fiscal year July 1 to June 30; FY27 bills are mailed in November. Counties shift dates when billing is delayed, so confirm against the county source linked on this page.
How much is property tax on a $400,000 house in New Castle County, DE?
About $2,964 a year, or $247 a month, at this county's effective rate of 0.74%. That rate is the county's median owner-occupied tax bill ($2,369) divided by the typical home value ($319,751). A seller's homestead or senior exemption usually does not transfer, so a new purchase can cost more.
What if I can't pay in full?
Most counties offer instalment plans or partial payment — ask the treasurer before the due date, not after. Once the bill is delinquent the options shrink and the fees start.
Does a late payment affect my mortgage?
Unpaid property tax is a lien on the property in most states, which your servicer may pay and then bill you for, with fees. It does not disappear.
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CountyTaxDates 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.