Potential Compensatory Costs Related to Invalid Spatial Planning in Communes. The purpose of the article is to compare the costs of enacted local plans and their possible repeal in the part concerning the faulty (irrational) allocation of land for various functions. It was attempted to estimate the costs associated with the hypothetical repeal of local plans in a situation where such a need arises, resulting from the overestimation of areas designated especially for housing development. These costs are primarily the need to pay compensation to landowners for those parts of the land that first changed their intended use from a lower market value to a higher one, and then there would be a hypothetical “reverse” operation (e.g. restoration of agricultural use). It was obtained that depending on the methodology, these costs could fluctuate between 135-325 billion PLN. This means that there is no possibility of ‘automatic’ repealing defective local plans across the all country.