Applying for any new loan can knock a few points off your credit score, but on-time payments will improve your score over time. New credit applications only account for about 10% of your FICO score, whereas your payment history makes up 35%.
Many refinancing lenders let you shop around with no impact on your credit score. With this pre-qualification, you can compare rates before submitting a full application and consenting to a hard credit inquiry.
Since you’ll be refinancing your current loans, rather than taking on new debt, your debt-to-income ratio should not be affected.