Delaware property tax deadlines
7 sourced dates. 3 of 3 Delaware counties have at least one.
In Delaware, each of the three counties (New Castle, Kent and Sussex) bills county and school tax once a year, and each sets its own due date. September 30 is usual, but the 2025 to 2026 statewide reassessment moved New Castle's dates by special law. Towns with their own property tax, like Wilmington, Dover, Rehoboth Beach and Lewes, bill separately on their own dates.
Next dates in every Delaware county
| County | Bills due | Last day without penalty | Appeal by | Exemption filing |
|---|---|---|---|---|
| Kent County, DE | Sep 30, 2027kentcountyde.govOct 21 | Not on file | Jan 31, 2027 Sunkentcountyde.govOct 21 | Not on file |
| New Castle County, DE | Dec 31, 2026legis.delaware.govOct 21 | Not on file | Mar 14, 2027 Sundelcode.delaware.govOct 21 | Not on file |
| Sussex County, DE | Sep 30, 2027sussexcountyde.govMay 17 | Not on file | Not on file | Not on file |
County dates
| Date and source | Deadline | Applies to |
|---|---|---|
| January 31 every yearkentcountyde.govOct 21 | Appeal deadline Your appeal must reach the assessment office | Kent County |
| March 14 every yeardelcode.delaware.govOct 21 | Appeal deadline Appeal your assessment to the Board of Assessment Review | New Castle County |
| September 30 every yearkentcountyde.govOct 21 | Bills due Yearly bill due | Kent County |
| September 30 every yearsussexcountyde.govMay 17 | Bills due Annual county tax bill due | Sussex County |
| December 31, 2026 2026 onlylegis.delaware.govOct 21 | Bills due 2026 county and school tax bill due | New Castle County |
| After the due date set by noticedelcode.delaware.govOct 21 | Paying late Late payment penalty After September 30 a penalty of 1.5% a month is added until you pay. | Sussex County |
| After the due date see ruledelcode.delaware.govOct 21 | Paying late Late payment penalty Late tax gets a 6% penalty, then 1% of the unpaid balance on the first of every month until you pay. | New Castle County |