This paper describes Visual Basic Application for customization of GIS software in order to develop sets of tools and utilities that are tailored-fit to the tax mapping and management of records of the real property units of Butuan City that could be utilized also in other developing countries. Visual Basic Application was employed to perform subdivision and consolidation of real property units (RPUs) within the GIS platform. These functionalities will enable users to automatically update the map and the database dynamically whenever an RPU owner declares conveyance of property either by subdivision or consolidation. VBA was further applied to automatically update the lot numbering of RPUs in an inverted “S” pattern whenever there is a need to re-section the tax map. On the other hand, an enhancement and customization was employed to automatically generate a tax map book for Butuan City. All developed applications were then integrated to give ease to the end-users. Upon simulations and testings conducted to the customized functionalities for the tax mappers of the City Assessor’s Office of Butuan City, it was therefore observed that an efficient, accurate, and effective tax mapping can change the paradigm as well as the quality of service of the City Government of Butuan, Philippines and any other local government units.