Please see Chapter 10.1.23 of the Medicare Billing Guide.
" Payment Source Changes From Medicare Advantage (MA) Organization to Original Medicare.
If a Medicare beneficiary is covered under an MA Organization during a period of home care, and subsequently decides to change to Original Medicare coverage, a new start of care OASIS assessment must be completed that reflects the date of the beneficiary’s change to this pay source. This is required any time the payment source changes to Original Medicare. With that assessment, an NOA may be sent to Medicare to open an HH PPS admission period. HHAs are advised to verify the patient’s payer source on a regular basis when providing services to a patient with an MA Organization payer source to avoid the circumstance of not having an OASIS to be used to determine the payment group, or having the patient discharged without an OASIS assessment.
If a follow-up assessment is used to generate a new start of care assessment, CMS highly recommends, but does not require, a discharge OASIS assessment be done.
While this is not a requirement, conducting a “paper” discharge at the point where the patient’s change in insurance coverage occurred will provide a clear endpoint to the patient’s episode of care for purposes of the individual HHA’s outcome-based quality reports. Otherwise, that patient will not be included in the HHA’s quality measure statistics. It will also keep that patient from appearing on the HHA’s roster report (a report the HHAs can access from the OASIS system that is helpful for tracking OASIS start of care and follow-up transmissions) when the patient is no longer subject to OASIS data collection.
In cases where the patient changes from MA coverage to Original Medicare coverage, the patient’s overall Medicare coverage is uninterrupted. This means an HH PPS period of care may be billed beginning on the date of the patient’s Original Medicare coverage. Upon learning of the change in MA election, the HHA should submit an NOA using the date of the first visit provided after the Original Medicare effective date as the “from” date. The OASIS assessment performed most recently after the change in election is used to produce a HIPPS code for the first claim in the new admission period.
If a new start of care (SOC) OASIS assessment was not conducted at the time of the change in pay source, a correction to an existing OASIS assessment may be necessary to change the reported payer source. The HHA should correct the existing OASIS assessment conducted most closely after the new start date. If more than one 30-day period has elapsed before the HHA learns of the change in payer source, this procedure can be applied to the additional periods. If the patient is still receiving services, the HHA must complete the routine follow-up OASIS assessments (RFA4) consistent with the new start of care date. In some cases, HHAs may need to inactivate previously transmitted assessments to reconcile the data collections with the new dates.
2. Payment Source Changes From Original Medicare to MA Organization
In cases where the patient elects MA coverage during an HH PPS period of care, the period will end and be proportionally paid according its shortened length (a partial period payment adjustment). The MA Organization becomes the primary payer upon the MA enrollment date. The HHA may learn of the change after the fact, for instance, upon rejection of their claim by Medicare claims processing systems. The HHA must resubmit this claim indicating a transfer of payer source using patient status code “06,” and reporting only the visits provided under the fee-for-service eligibility period. The claim through date and the last billable service must occur before the MA enrollment date. If the patient has elected to move from Original Medicare to an MA Organization and is still receiving skilled services, the HHA should indicate the change in payer source on the OASIS at the next assessment time point."