When does the law that congress passes The Monday Holiday Law which established the fourth Monday in October as the new date of observance of veterans day take effect?

The Monday Holiday Law, which established the observance of Veterans Day on the fourth Monday in October, took effect on January 1, 1971. However, this change was later reversed, and Veterans Day was officially moved back to November 11, where it remains today. The shift to November 11 was made to honor the original date of the armistice that ended World War I.