The 21 month transition period will end on December 31st, so make sure you are using Medicare Beneficiary identifiers (MBIs) now.
Providers are currently submitting 86% of claims with MBIs. Providers can get MBIs from your residents and through the MAC portals (sign up) now and after the transition period. Providers can also find the MBI on the remittance advice. Using the MBIs will help to protect your residents from identity theft.
Starting January 1, 2020 if you do not use the MBI (regardless of the date of service) for Medicare transactions, Medicare will reject your claims with a few exceptions and will also reject all eligibility transactions.
See the MLN Matters Article for more information on getting and using MBIs.