The Mass Real Estate Valuation Office enters data from contracts for real estate sale and purchase and rental transactions in the real estate market register, analyses the real estate market, and draws up reports on the real estate market. On the basis of data on the real estate market and mass valuation methods based on statistical and other mathematical methods, it develops and calibrates valuation models. It conducts procedures for determining valuation models according to prescribed criteria and keeps a record of such models. The valuation records include generalised real estate values calculated on the basis of real estate information and applicable valuation models (equations). In accordance with the administrative procedure, the Office decides on special circumstances affecting the value of real estate. It records the effect and duration of such circumstances in the valuation records.