Is zakat obligatory on an amount of ten thousand riyals, of which 500 riyals remain after purchasing household items, then the amount returns to ten thousand after receiving the salary?

Among the conditions for the obligation of zakat on money is the passage of a complete year (hawl) on possessing the nisaab, as the Prophet (peace be upon him) said: "There is no zakat on wealth until a year passes over it." If the money falls below the nisaab during the year, the year is interrupted, and zakat is not obligatory on it. If the money reaches the nisaab again, a new year begins to be calculated from the moment it reaches the nisaab. So, there is no zakat on money that has fallen below the nisaab, and a new year calculation begins when the money reaches the nisaab again.