The area of application of personal income tax exemption in cases of transfers of business shares, in which there was an increase in the investment in the given business corporation less than five years before its transfer, has recently become the subject of discussions among the professional public. The aim of this article is to present a deeper analysis of the possible interpretation of § 4 paragraph 1 letter s) ZDP, specifically in a situation where a partner increased his share in a business corporation by acquiring a share from another partner.