Hi all. I've recently become aware of the apparent limitations re: maintenance of a 5305-SEP while also having a Solo 401(k). I will try to spare you the unnecessary details and just hit the relevant points...
I have a small side business that is all but inactive at this point. I used to use a SEP-IRA for retirement savings related to this endeavor, but moved things to a Solo 401(k) in 2010. The SEP did, however, remain open (albeit empty) at that point. I made one additional contribution to the 401(k) after setting it up in 2010 but it has otherwise been essentially idle, just sitting there holding the existing funds.
In the intervening years, not having been aware of the restriction related to 5305 SEP-IRAs while maintaining a qualified plan, I made a handful of small-ish employer contributions to the SEP on my behalf. Don't ask why I did it this way, convenience or naïveté I guess.... Regardless, this was done during a time when there was no actual activity with the 401(k); again, I just made that one contribution after setting it up in 2010 and then left it alone.
So... Here we are.
Please note that I have no concerns about over-contributions or anything like that. The SEP contriibutions were safely below any relevant limits, and I never even contributed to both in the same year. Nonetheless, I have just discovered that these SEP contributions may not have been technically allowable, and am trying to figure out what (if anything) to do.
To complicate matters a bit further, I have since converted those (formerly deductible) SEP contributions to my Roth IRA. Thus, I actually wound up paying taxes on them, but the money is no longer in the SEP to "undo" if I wanted to somehow pursue that course of action.
One option would be to just do nothing and let this mistake fade into ancient history. This would have been the default course of action if I hadn't stumbled across the info alerting me to the potential problem. In this case, I probably would've gone through life none the wiser. Barring an audit in the near future (knock on wood) this issue would probably have been lost in the sands of time.
The other option would be to (somehow) fix it. The problem is, I'm really not sure how to undo this, or if it's even worth pursuing.