<prompt> Human: Ive spent the last seven years trying to pay off all of my loans. I have one loan left, a student loan at 6.25 with about 6,000 on it. I got a new job that dramatically bumped up my income, so Ill be able to pay this off pretty quickly.Im still trying to rebuild my credit. Im thinking about leaving a small balance on the loan to continue to build credit.Is this a good idea?How low can my balance be and still be allowed to make perpetual interest-only payments? i.e., Could I keep a perpetual 20 balance?Notes: Current credit score is about 700. I have two credit cards that I pay to zero balance monthly. I have no other loans, and have never had any long-term accounts. Navient Sallie Mae is my last, and longest-term loan. Ive never had a mortgage.  <response>: Interest is a fee you pay the bank to use their money. Stop worrying about your credit score and get out of debt. 