While a credit report is reviewed to provide a checks-and-balance on provided information, the credit score is NOT used in the qualification process.  If you are delinquent on any Federal debt, or have a lien including taxes, placed against your property for a debt to the United States, you are not eligible until the delinquent account is brought current, paid or otherwise satisfied.  While your property need not be debt-free to be eligible, any indebtedness from an existing lien must typically be satisfied at closing.