When someone has Medicare due to kidney failure and an employer group health plan, Medicare will be the secondary payer for 30 months from the earliest month that person is eligible for Medicare (this is called the Medicare secondary payer period). The clock could start the first month of dialysis if the patient starts home training prior to the first day of the third month of dialysis. However, if the perrson chooses to do in-center hemodialysis, the clock won't start until the third full month of dialysis making Medicare secondary for 33 months of dialysis.
If someone has Medicare due to kidney failure only, Medicare will last indefinitely as long as he/she is on dialysis and 36 months after a transplant. If someone turns 65 or is disabled and receiving Social Security Disability Insurance, Medicare will last indefinitely.
The main advantage of having Medicare Part B as a secondary payer when you have an employer group health insurance is that Medicare providers that accept assignment (agree to accept Medicare's allowable as payment in full) cannot bill patients for any deductibles, copays or coinsurance as long as the employer group health plan pays at least 100% of Medicare's allowed charge. Medicare's allowed charge for dialysis is about $135/treatment not counting drugs given during dialysis. Dialysis providers charge employer group health plans considerably more than this from what patients and some social workers tell me.
Another advantage for someone wanting a transplant is that Medicare Part B will cover anti-rejection drugs as either a secondary payer (when the patient has an employer plan) or or primary payer (after the end of the the Medicare secondary payer period):
1) If the person has the transplant at a Medicare approved transplant hospital and
2) If the person has Medicare Part A at the time of the transplant.
Obviously, your husband would have to have Medicare Part B in effective at the time he wants Medicare Part B to pay for these expensive drugs.
Finally one of the biggest advantages to having Medicare when you have an employer plan is that it protects your husband from having no health insurance coverage if anything unforeseen happens with your job or if the employer coverage changes. It's best to go to providers where your insurance pays the most, however, Medicare offers freedom of choice of providers in the U.S. or its territories. If an employer plan limits providers there is the option to use Medicare only. However, keep in mind that there are deductibles and copays or coinsurance for Medicare if it's the only payer.
If your husband is considering taking Part A without Part B, Social Security policies advise people to sign up for Part A and Part B at the same time either when first eligible or to start when the Medicare secondary payer period ends. Otherwise, if your husband takes Part A without Part B, which some people want to do to save the money on Part B premiums and to have Medicare Part A at the time of transplant, the only time he could sign up for Part B is during the general enrollment period (January thru March) with Medicare Part B taking effect the following July 1. And if he waits longer than 12 months to sign up for Part B after enrolling in Part A, there is a 10% penalty that is added to the premium each year for each 12 month delay.