I say, and with Allah's success: The threshold of wealth that requires Zakat al-Fitr is that one must possess the nisab of zakat, even if it does not grow. Growth is considered over a year with the value of gold and silver and money, or the grazing of livestock, or the intention of trade in goods. Real growth of the nisab is not a condition; that is, increase through birth, reproduction, and trade is not necessary. Rather, what is required is estimated growth, which is the ability to increase by having the money in one's hand or in the hand of a representative. Whoever possesses a nisab of zakat: any surplus nisab beyond their essential needs, whether it is in gold, silver, money, livestock, or trade assets, is obligated to give the zakat even if a year has not passed. If it is from other assets, such as a house that is neither for residence nor for trade, and its value reaches the nisab, Zakat al-Fitr is required from it even though zakat is not obligatory on it. With this nisab, it is also forbidden for him to take charity and zakat that are designated for the poor; this is a nisab of deprivation, unlike the nisab of zakat obligation, which requires growth. Refer to: Al-Wiqayah p. 229, Umdat al-Ri'ayah 1: 302, and Al-Talimat Al-Mardiyyah p. 198, and Allah knows best.