The article examines how the changes in the Ukrainian legislation regarding the conduct of settlement and cash discipline affected the current situation on the market. Systematized information on the correct organization of accounting and cash discipline at enterprises. We considered the peculiarities of the use and registration of settlement transaction registrars and software settlement transaction registrars in the activities of business entities, the procedure for their operation in various business environments. We determined the main differences of various software and technical complexes that provide calculation operations. The conduct of accounting and cash discipline in Ukraine was formed under the influence of old stereotypes and did not include full control over the movements of entrepreneurs' funds. Accordingly, it became clear that the situation cannot remain as it is, therefore the legislative apparatus introduces a number of changes and restrictions regarding the transparent display of settlement transactions. All innovations, in the vast majority of cases, were made to bring business out of the shadows, fiscalization of revenues, and replenish the state treasury with unpaid taxes. Although they were implemented recently, they have already fundamentally changed the procedure for conducting settlement operations. Therefore, regarding certain accounting issues, there are a large number of clarifications by tax authorities, articles by analysts and practitioners who place them in popular magazines, etc. That is, if a business entity has any misunderstandings regarding the correctness of accounting for certain transactions, he can always get advice from the tax authorities, which can be used later in court. Along with the existing changes regarding the mandatory use of settlement transaction registrars or software settlement transaction registrars (hereinafter RST and SRST, respectively), the economic situation in the country has become very unstable, since on February 24, 2022, a full-scale armed attack was carried out on Ukraine by the Russian federation, as a result of which, on the same day, martial law was introduced by Decree of the President of Ukraine No. 64/2022. The rules of doing business have changed radically, many Ukrainians were forced to leave their native homes, many people went abroad, some moved to safer regions. The result of this was the mass termination of the activities of many enterprises, and in those that remained, the volume of turnover decreased, standard work patterns were subjected to significant transformations. Despite this, entrepreneurs must continue to use RST and SRST during settlement transactions. There were no cancellations or postponements for the duration of martial law. Therefore, the study of the peculiarities of the use and registration of RST and SRST in the activities of subjects who are still working or those who want to start their business in this difficult time, in fundamentally new conditions of the external environment, determines the relevance of scientific research.