Government today has benefited from information technology in many ways. The importance of understanding and influencing citizens' acceptance of e-government services is critical, given the investment in technology and the potential for cost saving. Using the filing of personal income tax in Taiwan as an example of e-government services, this study integrated two important theories (TAM and TPB), and discussed the factors affecting the taxpayers' intention to adopt a particular tax-filing method (from manual, two-dimensional barcode, or Internet) based on empirical data gathered from a large-scale nationwide survey. The demographic characteristics and perceptions of the taxpayers were also explored in order to identify potential determinants. Results indicated that taxpayers tend to concentrate on the usefulness of a tax-filing method and may be fairly pragmatic in developing general attitudes towards using the method. Interestingly, the effects of perceived ease of use, subjective norms, and self-efficacy on behavioral intention were different for manual and electronic tax-filers. Understanding these factors can extend our knowledge of taxpayers' decision making and lead to better planning and implementation of e-government services.