Assalaam aleykum. I am able to meet the minimum requirements of my job, but I am not able to excel in it because of a few deficiencies in me. I worry because I have hidden or lied about some of these deficiencies during the interview. Does this make the earnings of my job haram?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger. 

Lying in the interview about some deficiencies that you have is a mistake and a sin that requires repentance.

What you are required to do now is to perform your job as required in the employment contract. If you do so, then your salary is lawful (halaal), and you are not obliged to excel in it.

If you cannot meet the obligatory requirements of your job, then deserving your whole or part of your salary depends on the terms of the employment contract. Based on those terms, your employer has the right to deduct from your salary in proportion to your failure to meet these requirements.

Allaah knows best.