A SEP-IRA is certainly different, but because both would be treated to be plans under the same employer (you as self-employed), the $58,000 per-employer limit applies. Also, because you are considered to be self-employed for the purpose of the 403(b), you are not permitted to have a separate SEP plan that is based on Form 5305-SEP for the plan agreement. Any SEP plan would have to be based on some other prototype SEP agreement, but the $58,000 limit on the combined contributions would still apply.
