OpenTaxSolver (OTS) is a free program for calculating Tax Form entries and tax-owed or refund-due, such as US Federal or State personal income taxes. An optional graphical front-end, OTS_GUI, has been added. Preliminary versions for Canada and the United Kingdom were posted in previous years and may be updated with help from volunteers. Motivations include: * To make tax preparation software available for all platforms. * To provide insight into how our taxes are calculated in clear unambiguous equations/code. * To avoid invasive, bloated commercial software packages. * To avoid rewriting our own individual programs each year by combining efforts. * To provide a simple reliable tax-package requiring only rudimentary knowledge to maintain.