Change of date of birth in documents

asalamualaikum. i have a close person to me whose date of birth was mentioned 1 year younger by her parents . later on , at the age of 15, she changed it to one more year younger while looking at the dob of other classmates, she didn't know that it was a sin and is haram. she is very repentful about it and want to know that she is a doctor and the date of birth will not effect her normal work , but can affect her retirement age if she gets a government job , so if she pre-retires 2 years earlier, will her rest of the income be halal as it most likely is not dependent on her date of birth and will the rest of her income be halal which is independent of her dob ? jazakallah khair .