Question: We have posted everything available from the Centers for Medicare and Medicaid Services (CMS) for our Medicare patients to ensure that they know to bring their new Medicare Beneficiary Identifier (MBI) number and card once they receive it, but when do providers have to switch to using the MBI exclusively? Tennessee Subscriber Answer: You should start using the MBI number as soon as you’re aware that any individual patient has received one. The MBI number is designed to improve security for Medicare beneficiaries and help protect their identities by providing a different means of identifying each patient rather than their Social Security numbers or the health insurance claim number (HICN), which is based on Social Security numbers. All of the MBIs should have been distributed by April 2019, so all of your patients should have their MBIs available. Note that the MBI looks very different from the HICN. Just like with the HICN, the MBI hyphens on the card are for illustration purposes: don’t include the hyphens or spaces on transactions. The MBI uses numbers 0-9 and all uppercase letters except for S, L, O, I, B, and Z,” according to a bulletin released by the Medicare Learning Network (MLN) on March 6, 2019. “Don’t use hyphens or spaces with the MBI to avoid rejection of your claim. The MBI will replace the HICN on Medicare transactions including Billing, Eligibility Status, and Claim Status. The effective date of the MBI, like the old HICN, is the date each beneficiary was or is eligible for Medicare. Until December 31, 2019, you can use either the HICN or the MBI in the same field where you’ve always put the HICN,” MLN says.