It is possible but if you are using Microsoft Project 2003/2002, only custom fields that are available across all projects in the Microsoft Project database file (.MPD file) are available for mapping. If you are using Microsoft Project 2007, only custom fields that are available across all projects (.MPP files) in the Microsoft Project folder are available for mapping. Calculated Microsoft Project custom fields cannot be mapped to Web TimeSheet user defined fields because Web TimeSheet user defined fields cannot perform calculations.

Mapping between Web TimeSheet user defined fields and Microsoft Project custom fields is dependent on the field type. This means that data transfer may fail if the data types are not compatible. For example, a number field cannot successfully transfer data to a date field; however, a number field can successfully transfer data to a text field.