42 CFR §411.43

1. (a)The beneficiary is responsible for taking whatever action is necessary to obtain any payment that can reasonably be expected under workers' compensation.
2. (b)Except as specified in § 411.45(a), Medicare does not pay until the beneficiary has exhausted his or her remedies under workers' compensation.
3. (c)Except as specified in § 411.45(b), Medicare does not pay for services that would have been covered under workers' compensation if the beneficiary had filed a proper claim.
4. (d)However, if a claim is denied for reasons other than not being a proper claim, Medicare pays for the services if they are covered under Medicare.