An interactive knowledge based system for monitoring international tax status has a residency status analyzer and a tax treaty analyzer that cooperate to determine the residency status of an individual, based on the individual's visa history, travel to and from the US, and the applicability of any treaty for the individual. The residency analyzer evaluates visa history, travel and days in the US, as well as type of activity and any applicable treaty's tie-breaker rule to determine if residency status is affected and sets indicators accordingly. The tax treaty analyzer performs an income type analysis to determine if income is from employment services, self-employment, or scholarship and fellowship grants. The tax treaty analyzer evaluates the applicable treaty for the presence and terms of a saving clause. For each type of income, the Tax treaty analyzer determines whether treaty benefits are available for the individual based on the primary activities of the person, and the person's residency status. Results are displayed interactively and also sent electronically to several output files and formats, including appropriate tax forms, files to be sent to an institution's payroll system, and audit trails.