No credit card required
Browse credit cards from a variety of issuers to see if there's a better card for you.
Whatever you made on your paychecks from 1/1/2016 to 12/31/2017 goes on your 2017 taxes as earned income.
Whatever you made on your paychecks from 1/1/2015 to 12/31/2016 went on your 2016 taxes as earned income.
And so on, regardless of the number of different jobs you had. Income is income.
Did you apply for PAYE/IBR or another income contingent payment within the past few months? What did they ask for as far as income documentation? I think they'll want your 2016 tax infor to caclulate your payments.
Or did they ask for some of your most recent paychecks, and you're making a lot more now than you were in the last tax year? Is that it?
Good luck.