Is employer-sponsored insurance required to meet a minimum standard in order to be used to defer Medicare Part B enrollment?

Yes, but only if the employer has 20 or more employees. If your employer has fewer than 20 employees and therefore is not required to provide minimum essential coverage, then Medicare will likely not let you defer Medicare Part B enrollment without a penalty. If you are unsure, contact your employer’s Human Resources department as well as the Social Security Administration to see if you will face any penalties for staying on your specific employer-sponsored insurance plan.