RMSA stands for Retirement Medical Savings Account. This plan may be offered by an employer and provides savings for healthcare costs in retirement.
Plans are unique to each employer. For specifics on an RMSA offered by your company, contact your Human Resources or Benefits department.
Generally the account will be funded by after-tax employee contributions and can include contributions from the employer. Access to funds is available after retirement and can be restricted to a specific age (ex. 65).