The issue of payroll and US tax withholding is one of the first practical issues a U.S. employee may encounter when they move abroad. Historically, these issues would have been ironed out on the backend by a dedicated HR office. Now, digital nomad visas and a general increase in global mobility make it possible for individuals to create their own opportunities to expatriate. In so doing, they take on risks that traditional expatriates whose companies handled their international transfer didn’t have to deal with. 

If you’re moving abroad and you own a US home, timing matters. Sell before foreign tax residency begins and you may keep the full §121 exclusion—sell after, and the math can change fast.