The app automates the IRS Substantial Presence Test, which calculates residency status based on weighted time spent in the U.S. over a three-year period. By tracking travel history, users can avoid the financial pitfalls of accidentally crossing residency thresholds that could jeopardize their status or provincial health coverage. Lucas Wennersten of 49th Parallel Wealth Management noted that the firm developed the software after observing too many clients relying on informal notes and memory to manage high-stakes border compliance.

Functionality includes a tap-to-log calendar, real-time projections of remaining "safe days" for the year, and direct links to official IRS and CRA guidance. To address privacy concerns, all data remains stored locally on the user's device rather than on external servers. The tool is available for web download and is rolling out on the Apple App Store, with an Android version expected to follow shortly. While the app provides a framework for planning, developers emphasize that it functions as a calculator rather than a substitute for formal tax or legal advice.