Real Estate Law · Allegheny County
Allegheny County Property Assessments: The 2012 Base Year, the CLR, and What Triggers a Reassessment
Allegheny County has not conducted a countywide reassessment since 2012. Every parcel in the county still carries an assessed value tied to market conditions from more than a decade ago. Property values have increased dramatically during that time, but the assessments themselves have remained anchored to the 2012 base year.
That gap between assessed value and actual market value now has a measurable number. The Pennsylvania State Tax Equalization Board calculates the Common Level Ratio each year based on real estate sales. For 2026, Allegheny County’s CLR is approximately 50.14 percent, meaning assessed values represent roughly half of current market value on average.
A property sale, deed transfer, or estate distribution can trigger reassessment in Allegheny County. When that happens, the new assessed value may reflect current market value rather than the 2012 base year.
Call 412-351-4422 or schedule a consultation before recording a deed or completing a property transfer.
The 2012 Base Year
Pennsylvania law allows counties to use a base year system for property assessments. Under this system, the county establishes a baseline year for valuation and maintains those values until a countywide reassessment occurs. Allegheny County’s base year is 2012.
As a result, many long-term property owners pay taxes based on values that reflect market conditions from more than a decade ago. A home that might sell today for $400,000 may still carry an assessed value closer to its 2012 price.
This disparity between assessed value and current market value is the natural outcome of a base-year system operating in a rising real estate market.
The Common Level Ratio
The Common Level Ratio is the legal mechanism that attempts to maintain uniform taxation in a base-year county. Each year the Pennsylvania State Tax Equalization Board reviews recent property sales and calculates the relationship between assessed values and actual market prices.
Allegheny County’s 2026 CLR is approximately 50.14 percent. In practical terms, this means the county’s assessments represent about half of current market value on average.
In an assessment appeal, property owners may use the CLR to argue that the assessed value should reflect the countywide relationship between assessments and market prices.
What Can Trigger Reassessment
While the 2012 base year remains in place for many properties, certain events can bring a property back in front of the assessor. A sale of the property is the most common trigger. When a property sells, the county may reassess it based on the sale price rather than the historic base-year value.
Other recorded transfers can also attract attention. Deeds transferring property between family members, transfers into an LLC, or distributions of real estate through an estate administration may result in the county reviewing the property’s assessed value.
Whether a reassessment occurs depends on how the county processes the transaction, but the possibility should always be considered before a deed is recorded.
Two Different CLR Calculations
Allegheny County property owners sometimes encounter two different CLR-related numbers that operate in opposite directions.
The appeal CLR — currently about 50.14 percent — is used when challenging an assessment. It reflects the relationship between assessed values and market prices across the county.
A separate factor is used when converting assessed values to estimated market values for certain legal purposes, including realty transfer tax calculations and inheritance tax reporting. That factor may produce a number much closer to current market value.
The distinction is important for property transfers and estate administration because the value used for tax reporting may differ significantly from the value shown on a property tax bill.
Potential Changes to the System
State lawmakers have periodically proposed legislation requiring counties to conduct reassessments at regular intervals. If such legislation passes, Allegheny County would eventually move away from the 2012 base year and reassess all properties based on current market conditions.
Until that occurs, the base-year system will continue to produce disparities between long-time property owners and more recent buyers.
Related: This article explains how Allegheny County’s base-year assessment system and the Common Level Ratio affect property taxes. For the hearing process and evidence required in an assessment appeal, see our article on Allegheny County Property Assessment Appeals. For guidance on real estate transfers and title issues, see our Real Estate Transactions and Real Estate Issues pages. For inheritance tax considerations when real estate passes through an estate, see our Pennsylvania Inheritance Tax page.