When was my Pennsylvania county last reassessed?

Because Pennsylvania is the only state without a reassessment mandate, the year your county last did a countywide reassessment — its base year — varies enormously. Some counties last reassessed in the 1960s; others have completed recent reassessments. There is no single statewide schedule.

Why the base-year age is the appeal opportunity. When a county freezes values for decades under 53 Pa.C.S. §8842, neighborhoods appreciate at different rates while the base-year assessments stay fixed. The result is widening unfairness between similar homes. The State Tax Equalization Board's annual Common Level Ratio measures how far, on average, base-year assessments have fallen below current market value — and a low CLR signals a stale base year ripe for appeals.

How to find your county's base year and reassessment status. Check your county assessment office's official website, which states the base year used and whether a reassessment is underway. A handful of counties periodically announce new countywide reassessments, which reset everyone's values and often trigger a wave of appeals from owners whose new numbers overshoot.

Two examples of distinct county systems:

• Allegheny County continues to rely on a 2012 base year, adjusting toward current value through the CLR (50.14% for 2026). See Allegheny County.
• Philadelphia reassesses far more frequently than most counties, with countywide reassessments in recent years; appeals run through the Board of Revision of Taxes.

Bottom line: if your county's last reassessment is old, don't assume your frozen number is fair. Pull your county's current CLR, estimate your true market value, and run the comparison — old base years are where over-assessment hides.