The primary goal of this thesis is to point out the problems of maintaining business applications in the conditions of ever-changing legally prescribed tax regulations, and to develop a new model for developing and maintaining business applications. Long-term trends in tax policies tend to change frequently, and such trends directly affect the information systems maintenance. On the other hand, the development of information and communication technology, the development of programming languages and database systems requires new contemporary approaches in the concept and methods of development, management and maintenance of information systems. All of this together contributed to the fact that the main feature of the proposed new model is to reduce the time required to develop and maintain applications, while increasing business functionality under the conditions of legal changes or user requirements. By applying appropriate scientific methods, the intention is to deepen the concept and importance of adaptive maintenance and extend the life of business applications. The approach proposed in the doctoral thesis, called the “Transformation Model”, meets this fully. The rule base into which rules are entered and updated through the knowledge acquisition mechanism makes up the components of the transformation model that allow the behaviour of the system to change by selecting the relational scheme, depending on the date criteria of the user's queries, while maintaining the integrity of the data. Maintenance of business applications is a continuous process that continues after the completion of the development and submission of the information system into the exploitation. The continued exploitation of the information system largely depends on maintenance. The transformation model provides additional quality and constant support in terms of controlling and correcting business process records by the user in real time.