Income-Based Repayment Option

I have a quick question regarding the new IBR plan and I was hoping someone could help me out with it.

 

I have about $100K in Fed Student Loan (75% subsidized and 25% unsubsidized) currently.  At an average interest rate of about 5%, I’m assuming the interest on the loan will be about $5000/year. 

 

Hypothetically speaking, if I take a job in the public sector making ~$40K/year and choose the IBR option, my monthly student loan payment will be approximately ~$300/month or $3600/year.  So if I’m understanding this correctly, this would mean that my outstanding balance will increase each year, resulting in my owing more than the original amount.  

 

So here’s my question: how does owing more than the original amount affect my credit score?  I read somewhere that it’s going to lower my credit score.  If this is true and I choose to stay in the public sector hoping to have my loan forgiven in 10 years, does this mean that I’ll have poor credit score during those 10 years?  

 

I hope that made sense.  

 

Thanks in advance.