In 1918 a "kaoku-zei" decree was issued. It introduced a tax system for the housing in Kyoto city. This official order established also a tax free delay for the new letting buildings built in an urban area. I undertook the study of this clause considering the application of this tax delay on the housing policy. The outline of this paper is as follow : 1. I will have it about the contents of this tax exemption clause for this kind of buildings and its establishe-ment process. 2. It will be about the revision of this official order in 1922 which enlarged the application field of this tax dispensation. 3. It will be about the revision of 1926 which shortened its time-limit. 4. It will be about the exemption characteristics of the "kaoku-zei" and the function it fulfilled.