Summary Plan Descriptions 2021 Merck Flexible Spending Accounts Summary Plan Description 2021 Merck Medical Plan for Employees Summary Plan Description 2021 Merck Medical Plan for Retirees Summary Plan Description 2022 Merck Flexible Spending Accounts Summary Plan Description 2022 Merck Medical Plan for Employees Summary Plan Description 2022 Merck Medical Plan for Retirees Summary Plan Description