<p><p><p><p>The FORTAX project is centered around the development of the FORTAX library, a micro-simulation tax library programmed in Fortran. It represents an on-going research project that aims to provide researchers the ability to calculate detailed representations of the UK tax and transfer systems over time, incorporating the complicated rules and interactions. The library is highly efficient and flexible, and is ideally suited to applications where accurate budget sets or components of income need to be calculated repeatedly. The estimation and simulation of labour supply models are therefore natural candidates for the use of FORTAX.</p></p></p></p>