Self-diagnosis in psychiatry is where individuals diagnose themselves rather than rely upon official diagnosticians to supply a psychiatric diagnosis. The accuracy of self-diagnosis is a contested topic. In this paper, I outline what arguments are needed to see self-diagnosis as accurate and how different approaches to self-diagnosis require different arguments. I show how different arguments are required to justify accuracy for an autistic individual judging they are autistic compared to non-autistic individuals judging they are not autistic. Different arguments are required if a self-diagnosing individual accepts or rejects official diagnostic criteria. Finally, different arguments are required depending upon whether diagnoses are seen as objective entities, the product of theoretical virtues or practically useful groupings. All these approaches require unique arguments to justify the accuracy of self-diagnosis. Identifying the required arguments for different approaches is a stepping stone toward establishing whether those arguments and which of those arguments can be successfully justified.