What is the ruling on forging a certificate of residency to change school institutions, and the ruling on completing studies in that high school and benefiting from its certificate after graduation?

Forgery is Haram (forbidden), whether for educational purposes or otherwise, due to the generality of Allah’s saying: "So avoid the impurity of idols and avoid false statement." It is obligatory to adhere to the standards set by educational institutions. Whoever transgresses them must repent to Allah. If he is still studying, he should inform the responsible authority about the transgression, unless that would lead to a greater harm. However, if he has already graduated, forgery does not prevent benefiting from the certificate, as there is a disconnect between the two matters.