Example. B, a citizen of foreign country F, enters the United States on April 1, 1985, as a lawful permanent resident. On August 1, 1987, B ceases to be a lawful permanent resident and returns to country F. B meets the initial residency period requirement because he is a resident of the United States for at least 183 days in each of three consecutive years (1985, 1986 and 1987). B returns to the United States on October 5, 1990, as a lawful permanent resident. Because B became a resident of the United States before the close of the third calendar year (1990) beginning after the close of the initial residency period (August 1, 1987), he is subject to tax under section 877(b) for the intervening period of nonresidency, August 2, 1987 through October 4, 1990, if the amount of the tax imposed under section 877 is more than the tax imposed under section 871.
26 C.F.R. §301.7701(b)-5