What are the exceptions to Medicare's general timely filing period?

Medicare regulations at 42 CFR section 424.44(b) allow for the following exceptions to the 1 calendar year time limit for filing fee for service claims:

Administrative error, if failure to meet the filing deadline was caused by error or misrepresentation of an employee, Medicare contractor, or agent of the Department that was performing Medicare functions and acting within the scope of its authority.
Retroactive Medicare entitlement, where a beneficiary receives notification of Medicare entitlement retroactive to or before the date the service was furnished. For example, at the time services were furnished the beneficiary was not entitled to Medicare. However, after the timely filing period has expired, the beneficiary subsequently receives notification of Medicare entitlement effective retroactively to or before the date of the furnished service.
Retroactive Medicare entitlement involving state Medicaid agencies, where a state Medicaid agency recoups payment from a provider or supplier 6 months or more after the date the service was furnished to a dually eligible beneficiary. For example, at the time the service was furnished, the beneficiary was only entitled to Medicaid and not to Medicare. Subsequently, the beneficiary receives notification of Medicare entitlement effective retroactively to or before the date of the furnished service. The state Medicaid agency recoups its money from the provider or supplier and the provider or supplier cannot submit the claim to Medicare, because the timely filing limit has expired.
Retroactive disenrollment from a Medicare Advantage (MA) plan or Program of All-inclusive Care of the Elderly (PACE) provider organization, where a beneficiary was enrolled in an MA plan or PACE provider organization, but later was disenrolled from the MA plan or PACE provider organization retroactive to or before the date the service was furnished, and the MA plan or PACE provider organization recoups its payment from a provider or supplier 6 months or more after the date the service was furnished.