Performing Salaah On Behalf Of Deceased Parents

If the purport of your query is whether one can perform Nafl Salaah and convey the reward therof to one’s parents, then that is permissible, in fact meritorious to do so.

However if the purport of your query is to ascertain whether one can perform on behalf of one’s parents any Fardh/obligatory Salaah that was outstanding on their shoulders and assume that this will absolve them of the responsibility of that missed Salaah, then this will not be permissible. In essence, it is impermissible to perform Fardh Salāh on behalf of any deceased person who had any outstanding Fardh Salaah.

However, if one wishes to dispense his/her parent’s missed Salāh by way of Fidyah (monetary compensation) he/she may do so.