If you see doctors often, or have tests regularly, your medical costs could be high. Visiting a doctor or having tests will cost you less once you reach the Medicare Safety Net threshold. The Medicare Safety Net threshold is made up of money you and your family have spent on any item to which a Medicare Item number applies.
These include - 
Healthcare Professional Consultations
GPs
Specialists
Some Allied Health Practitioners
Blood Tests

CT Scans

Radiotherapy

Tissue Biopsies

Ultrasounds

X-Rays

This does not include costs incurred whilst a patient in hospital.

The Medicare Safety Net Threshold is dependent on your financial circumstances.  If you are a concession card holder or receive family tax benefit part A, the Medicare Safety Net will be activated once your family have spent $697.00 in out of pocket expenses. For all other people the Medicare Safety Net is activated once your family has spent $2184.30  in out of pocket expenses. Once you and your family have reached the threshold, a higher Medicare benefit will be paid for all eligible services for the rest of the calendar year. This will mean that visits to your doctor or having tests will cost you less.

Please note you need to register for the safety net each year.

More Information-

Medicare Safety Net

Medicare Safety Net