You may have to pay the Medicare levy surcharge if:

• you, your spouse and your dependent children do not have an appropriate level of private patient hospital cover; and
• you earn above a certain income.

The MLS is an amount you pay on top of the Medicare levy.  If you take out an appropriate level of private patient hospital cover for yourself, your spouse and all your dependants, you will not pay the MLS.

You can view the current and past income thresholds & rates as well as some examples here:  https://www.ato.gov.au/individuals-and-families/medicare-and-private-health-insurance/medicare-levy-surcharge/medicare-levy-surcharge-income-thresholds-and-rates