53 Pa. Stat. § 7334
Whenever after due investigation, it has been determined by the corporate authorities of any county, city, borough, incorporated town, township, school district or institution district, that the fair market value of any property against which such political subdivision has theretofore entered a lien for municipal improvements or for the abatement of nuisances, or against which such political subdivision has secured judgment by revival of a lien theretofore entered, is insufficient, in the judgment of the corporate authorities of such political subdivision, to realize the amount thereof at a sheriff's sale of the same, such portions of the interest, penalties, and total debt of said claim, as in the judgment of said corporate authorities may be uncollectible from said property, may be abated by the political subdivision in behalf of which the claim was filed: Provided, however, That no such abatement of any portion of the debt, interest or penalties shall be made except in cases where immediate payment of the reduced amount with costs is made in cash to such political subdivision: And provided further, That no such abatement shall be made unless the same is authorized by a resolution passed by a two-thirds vote of the corporate authorities of the county, city, borough, incorporated town, township, school district or institution district so abating the same.
53 P.S. § 7334