When is my property tax appeal due?

Missing the deadline is the most common way an appeal fails — not a weak argument, not bad comparables, a date. This gives you yours in 51 jurisdictions, with the statute it comes from and a calendar reminder.

Every deadline rule we hold

Quoted from the statute rather than summarised, because the wording is what decides whether you are on time.

State	The rule
Alabama	Within 30 days of the date on the valuation notice.
Alaska	Within 30 days of the assessment notice (borough/municipal ordinance may vary).
Arizona	Administrative appeal to the assessor within 60 days of the notice of value; or file directly with Tax Court by December 15.
Arkansas	Petition the county equalization board on or before the third Monday in August.
California	July 2 – September 15 in counties that mail notices by August 1; July 2 – November 30 elsewhere. Confirm your county.
Colorado	Protest to the assessor by June 8; appeal to the County Board of Equalization by September 15.
Connecticut	Written appeal to the Board of Assessment Appeals by February 20.
Delaware	Set by county ordinance, typically within 30 days of the notice.
District of Columbia	First-level appeal to OTR by April 1.
Florida	Petition the Value Adjustment Board within 25 days of the TRIM notice (typically mid-September).
Georgia	Within 45 days of the annual notice of assessment.
Hawaii	January 15 on Oahu; confirm your county.
Idaho	On or before the fourth Monday in June.
Illinois	30 days from the publication of your township's assessment roll in the local newspaper. The window is short and it is not the same date across the county.
Indiana	File Form 130 by June 15 of the assessment year if the notice was mailed before May 1; otherwise within 45 days of the notice.
Iowa	Protest to the Board of Review between April 2 and April 30.
Kansas	Within 30 days of the notice of value, or protest at payment time.
Kentucky	Conference with the PVA during the 13-day inspection period beginning the first Monday in May.
Louisiana	During the public inspection period (typically 15 days in August–September), then to the Board of Review.
Maine	Within 185 days of the commitment date.
Maryland	Within 45 days of the notice of assessment; otherwise a petition for review by January 1.
Massachusetts	Abatement application due by the due date of the first actual (not preliminary) tax bill — commonly February 1.
Michigan	March Board of Review — usually the second or third week of March. Appearing before the March board is a prerequisite to a Tax Tribunal appeal for residential property.
Minnesota	Local Board of Appeal and Equalization in April, or Tax Court by April 30 of the year the tax is payable.
Mississippi	Objection to the Board of Supervisors at the August meeting when the roll is equalized.
Missouri	Appeal to the Board of Equalization by the second Monday in July.
Montana	Form AB-26 request for informal review within 30 days of the classification and appraisal notice.
Nebraska	Protest to the County Board of Equalization between June 1 and June 30.
Nevada	Appeal to the County Board of Equalization by January 15.
New Hampshire	Abatement application to the selectmen or assessors by March 1 following the notice of tax.
New Jersey	April 1 (May 1 in a municipality that has completed a revaluation or reassessment); January 15 for added assessments in some cases.
New Mexico	Protest within 30 days of the notice of value.
New York	Grievance Day — the fourth Tuesday in May in most towns; New York City and some cities differ substantially.
North Carolina	Before the Board of Equalization and Review adjourns — typically April or May.
North Dakota	Local board of equalization in April, county board in June.
Ohio	Complaint (Form DTE 1) filed between January 1 and March 31.
Oklahoma	Within 30 calendar days of the notice of increase, or by the first Monday in May.
Oregon	Petition the Board of Property Tax Appeals by December 31.
Pennsylvania	August 1 or September 1 depending on the county class; Philadelphia is the first Monday in October.
Rhode Island	Appeal to the assessor within 90 days of the first tax payment due date.
South Carolina	Within 90 days of the assessment notice, or by January 15 in a year with no notice.
South Dakota	Local board of equalization in March.
Tennessee	County Board of Equalization, typically June; State Board by August 1.
Texas	May 15, or 30 days after the notice of appraised value was delivered, whichever is later.
Utah	On or before September 15, or 45 days after the valuation notice, whichever is later.
Vermont	Grievance to the listers within 14 days of the notice of change.
Virginia	Set by local ordinance — commonly within 30 to 60 days of the notice for the Board of Equalization.
Washington	July 1, or within 60 days of the notice of value, whichever is later.
West Virginia	Board of Equalization and Review meets in February; appeals must be made then.
Wisconsin	Objection filed with the Board of Review at or before its first scheduled meeting; written notice of intent is required.
Wyoming	Within 30 days of the assessment schedule.

Deadlines are the one thing here worth double-checking against your own notice and your county's website. Where a rule offers a range we take the earlier date, because being early costs nothing and being late ends the appeal.