The objective is to determine the financial implications of the introduction of the lump sum from revenues in agricultural farms. Concepts were proposed based on modeling-simulation of the effects of the introduction of a lump sum of the revenue in individual farms depending on their cropland area, the type of the agricultural and economic strength. The research period covers the years 2004-2009. The tax burden on the agricultural farms with the revenue lump sum was disadvantageous in all described criteria. It might be caused by the fact that in this form of taxation is not possible to decrease the costs of activities, which in the case of agricultural activity are relatively high.