The most you have to pay for covered services in a plan year. After you spend this amount on deductibles, copayments, and coinsurance, your health plan pays 100% of the costs of covered benefits.
The out-of-pocket limit doesn’t include your monthly premiums. It also doesn’t include anything you may spend for services your plan doesn’t cover.

References

https://www.healthcare.gov/glossary/out-of-pocket-maximum-limit/