Substantial gainful activity (SGA) is work which results in earnings over a certain monthly threshold. It also refers to work activity involving the performance of significant physical or mental duties, or a combination of both, which are productive in nature. If you work and are receiving an annuity based on a total and permanent disability, or if you have a period of disability (also called a disability freeze) or early Medicare, you may be subject to a finding of SGA as the result of a continuing disability review (CDR) determination. This may impact the continuation of your disability annuity, period of disability, and/or early Medicare. For a description of CDR, see Chapter 13. Also, refer to Form AB-31, How Work Affects Your Disability Annuity.