In the paper, formulas and numerical examples of real estate market value, for which legal limitations are assigned, have been shown. The paper presents an algorithm of calculating the local differential ionospheric and tropospheric corrections as well a method of considering this corrections in GPS phase measurements. In calculation process double difference of GPS phase observations is used as well as precisely estimated initial ambiguities of double difference phase measurements on $L_1$ and $L_2$ frequencies performed on reference points of known coordinates. Next this correction is taken into consideration in GPS measurements, that are carried out on the area limited by reference points. Quoted numerical examples illustrate the influence of ionospheric and tropospheric corrections on quality of obtained GPS vectors about length of 37-67 km. In computational experiments it use phase measurements performed on points of active geodetic network ASG-PL and research geodynamic network points in the eastern part of Upper Silesian Coal Basin.
