Ruling on changing one's date of birth in order to continue working
Question

                In our country, a person who reaches the age of 65 changes his birth certificate to show a younger age, so that he can carry on working. Is the salary that he takes haraam?.
Praise be to Allah.It is not permissible to 
    tinker with the date that is recorded on the birth certificate for the 
    purpose mentioned, because that involves deceit, lying and trickery in order 
    to carry on working unlawfully. 
If the employer stipulates 
    that the worker should be less than 65 years old, then it is obligatory to 
    adhere to this condition and it is haraam to use tricks to circumvent it. 
    Similarly, if the workplace lets people go when they reach this age, it is 
    essential to tell them and it is haraam to deceive them, because the Prophet 
    (blessings and peace of Allaah be upon him) said: “The Muslims are bound by 
    their conditions.” Narrated by Abu Dawood (3594), classed as saheeh by 
    al-Albaani in Saheeh Abi Dawood. 
And because of the general 
    meaning of the evidence which shows that deceiving and lying are haraam. 
And Allaah knows best.