The answer is not as clear as some have indicated. If you file as an S Corp and the SEP contributions are employer contributions reported on your S Corp return, they wouldn’t be considered untaxed income and wouldn’t show up on your personal return at all. They would reduce your pass through income though, resulting in a potentially significant tax savings. Different FA offices might treat this differently so it might be hard to know for sure in advance. Same might be true of employer portion of Solo 401k contribution but I’m not familiar with how that gets reported.