The cadastral assessment of real estate became relevant since 2013. The Russian legislation defines flats in townhouses ambiguously. They have the status of apartments in apartment house or the status of part interest in the ownership of dwelling houses. In this regard their status and the status of the land plots under them are different from one to another. Depending on the status of the flat in townhouse and the land under it, the authors suggest two methods of the cadastral assessment. It means that the land and the flat in townhouse may be assessed either together or isolated. The author uses math­ematic modeling for cadastral assessment. The attention is also paid to the change of parameters (like the area, the wall material, the building year) and its influence on the cadastral assessment. There is a possibility to improve the cadastral assessment in Russia.