Should she apply for social secutiry card?

[need_b2]

My wife has got her EAD card recently and both of ours I-485 is pending.
She is a medical doctor and can not work until she finishes all her licensing exams.
Is it advisable to apply for social security right now or should we wait till she is done with exams?

Are there any disadvantages( taxes etc) of having her social security card and not working?