Unless you’re making over $100,000 per year, it’s unlikely that you will owe any taxes to the American government. To qualify as a foreign worker, you need to be living abroad for 330 days out of the tax year. This rule exists because you may already be paying taxes to the country where you’re employed as a teacher and protects you from double taxation.
But even if your income falls below $100,000, you should still file a completed U.S. tax return. Indeed, not filing one could result in being audited by the IRS.