Is it permissible to record the amount of zakat paid as "donations" in the annual tax declaration to avoid paying taxes on it, and does the same ruling apply to sadaqat (charity) and contributions to mosque construction?

Zakat must be paid on zakatable wealth that has reached the nisab and on which a full year has passed. It is not permissible to evade paying taxes imposed in lands of kufr, because a Muslim is obligated to fulfill contracts and trusts. However, there is no harm in submitting documents proving that a portion of the money paid for taxes is from zakat funds, or charity, or contributions to building a mosque, and recording it as donations. This is not considered deception or evasion; rather, it is in accordance with the law, which does not differentiate between zakat money and charity.