In investigating the influence of structural engineering design software and fees on cost certainty of High-rise building, data was collected from 150 consulting civil engineers drawn from the Engineers Board of Kenya register using a web-based structured questionnaire survey. Descriptive and inferential statistics were used in data analysis and interpretation. Results showed that the greatest influence design software has on cost certainty of building projects is the accuracy of the pre-tender cost estimates used for procurement. Further only 9.4% of engineers used modern integrated design software because of the high purchase and licencing costs. Consequently, inaccuracies in pre-tender documents are perpetuated through limitations in modelling complex buildings, inflexibility in effecting design changes, and updating and synchronizing project documentation. Therefore incentives to discard stand-alone engineering design software in favour of integrated ones merit consideration. Although expensive, integrated software significantly reduce the risk of cost overruns. As such, they should be viewed as a necessary investment that enhances efficiency and overall quality of work. Further, whereas various approaches exist for paying the consultants, negotiations as dictated by free market systems are becoming popular, which calls for fidelity to professional ethics from contract signing and through the entire project cycle.