In this session I will illustrate how to create EXCEL add-ins that take full advantage of MATLAB’s extensive computational and visualization capabilities. EXCEL spreadsheets provide a broad array of fundamental tools but often come up short when more sophisticated scenarios are considered. To overcome this short-coming of EXCEL while retaining its ease of use, I describe how MATLAB’s EXCEL Builder converts MATLAB functions into EXCEL macros. The add-ins can be freely distributed and operate solely from EXCEL. To demonstrate the creation and use of the add-in, I will use a model that gives users information on ‘When to begin accepting social security checks’ (e.g. age 62?, 65?, 70?).