Derek

Added an edit to my post to clarify that I’m looking for professional assistance. Would love to work with anybody who is willing to help.

Edit: I’m happy to pay a professional to advise on how best to navigate the situation I’ve described below Would anybody here be willing to take this on? Or be able to refer me to somebody that can? I’ve reached out to a few professionals and unfortunately have not had any luck Thank you. Hello, I am self-employed and have been contributing to a solo 401k since 2022, but I think that I’ve made some mistakes that I need help resolving. I've asked my CPA and his 401k plan administrator, but they are unsure of how to help me. In January 2022 I opened a Traditional Solo 401k and Roth Solo 401k at ETrade. When setting up the accounts, I used Plan Numbers 001 and 002 as directed by ETrade. The Plan Sponsor was my sole proprietorship. I made zero contributions to the Traditional and $3,000 to the Roth. A few months later I decided to establish an S-Corp, and I opened up another Solo 401k account at Vanguard with the S-Corp as the sponsor. For this account I used Plan Number 001. Since I didn’t plan to operate the sole proprietorship any longer, I closed the two accounts at ETrade and rolled the Roth 401k balance into an existing Roth IRA that I hold at Vanguard. I am now realizing that I should have filed Form 5500-EZ after closing the ETrade accounts. I am also wondering if I may have violated the successor plan rule by erroneously considering the sole proprietorship and S-Corp to be separate employers rather than an affiliated / controlled group. Questions: Will I need to file two separate late returns using Form 5500-EZ and pay the associated $1,000 in penalties for the ETrade accounts that were closed? Or is it possible that I may only need to file one considering I made zero contributions to the Traditional account? Do the sole proprietorship and the S-Corp qualify as affiliated employers? If so, did I violate the successor plan rule by opening the Vanguard 401k within 12 months of terminating the ETrade accounts? What penalties would this incur and how would I rectify this? If the sole prop and S-Corp are affiliated, do I need to amend the plan sequence number on my current Vanguard solo 401k account to be 003?