Can the amount deducted from the salary, which is paid as a donation to the Children's Cancer Hospital, be considered an ongoing charity (Sadaqah Jariyah) for the soul of the deceased mother?

It is permissible to dedicate the reward of charity given on behalf of the sick to a deceased mother, whether it is from past or future acts of charity. The reward of such charity reaches her, according to the mainstream Sunni scholars (Ahl al-Sunnah (definition) wa al-Jama'ah). There is no difference between intending the charity for another at the time of giving it, or performing it for oneself and then dedicating its reward. However, the charity given with the mentioned amount is not considered an ongoing charity (sadaqah (definition) jariyah), because ongoing charity means holding the principal and making its benefit available. This implies that a specific asset is endowed for the poor to benefit from, and this asset remains endowed, not to be sold or gifted.