Was there a question about credit on your N-400? The issue that might be troubling is if you obtained any of the credit by fraud, by falsely representing yourself to be a US citizen.
I am certainly not aware of USCIS doing a credit check on N-400 application. You are not alone in terms having of bad credit! If you do owe taxes, you need to make payment arrangement with the IRS to pay it off or pay it off first.