Active Component (AC) Service members who do not choose to opt into the BRS by December 31 2018 will be?

Active Component (AC) Service members who did not opt into the Blended Retirement System (BRS) by December 31, 2018, will remain under the traditional retirement system, which provides a defined benefit based on years of service and the average of their highest 36 months of basic pay. They will not receive the BRS's additional features, such as the continuation pay and the Thrift Savings Plan (TSP) automatic and matching contributions. This means their retirement benefits will be calculated solely on the legacy system's parameters.