You may set the patient’s late charge as a percentage or a dollar amount, or you may decide to not charge late fees. Note that under Federal regulations, you MUST have proof that the patient was aware in advance that late fees/penalties will be charged if your bill is not paid on time. If you do NOT have that proof, do NOT charge a late fee or penalty. Proof is having a signed statement from the patient that would typically be included in the patient’s initial paperwork.