Do I have to pay off collections accounts before applying for a FHA loan?

Typically all collection accounts and judgements should be paid off before applying for a FHA mortgage. You should get prequalified by a mortgage professional before paying any items off.
Q - Can I get a FHA loan if I have a federal tax lien? A - You may qualify for a FHA loan even with a Federal tax lien, as long as it has been in a repayment schedule for at least 6 months and all payments have been made on time. The monthly payment will be counted against you as a monthly liability and will affect the amount of the loan you will qualify for. State tax liens must be paid off in full.