According to the standards of practice and medicare guidelines the date of service is when a finished product is delivered to a patient. No insurance or patient can be billed until a(n) item is actually provided to the patient. Whether the item is a simple ankle brace or a fully custom above knee prosthesis. In very special circumstances with very high end and costly items some insurance companies will allow a provider to bill for parts before delivery.
Patient's need to be cognizant of the date of service of goods they receive if they plan on needing another device in the future or if they are going to be liable for a co-poy, co-insurance, or deductible. Even though a patient goes in to be evaluated for a good and may think their deductible is met this may not be the case. Often times in the time from the initial evaluation to the time of delivery your benefits may change or reset. This is especially true around the first of the year or the calendar year when you insurance policy resets.