Whenever in any proceeding a judgment has been obtained on a tax claim, and the market value of the real estate or its market value above the amount of mortgages, ground rents, and other encumbrances, if any, which would not be discharged at a sheriff's sale for such taxes, is less than the total amount of all delinquent taxes and municipal claims against such property, the Board of Revision of Taxes or other authority empowered by law to fix the value of such property for taxation, acting as a board, may file in the proper court, to the term and number of the proceeding in which such judgment has been obtained, a certificate setting forth the fair market value of such real estate as determined by said board and the amount of liens and encumbrances, if any, except tax and municipal claims, which would not be discharged by such sale. Such valuation shall appraise the real estate as subject to the liens or encumbrances, or if there be no liens or encumbrances which would not be discharged by the sale, at the fair market value of the real estate free and clear of encumbrances. Such certificate may be executed by any member of the board designated by it and having the approval of the board.