Do I need an EIN for my LLC to open a Solo 401k or can I use my SSN as a sole proprietor?

Yes, you absolutely can open a Solo 401k as a sole proprietor using just your SSN! I work with self-employed clients on this exact issue all the time. The confusion happens because while the Solo 401k plan itself will eventually need an EIN (this is for the plan, not your business), you don't need an LLC with an EIN to establish one. As a sole proprietor operating under your SSN, you can establish a Solo 401k and then apply for an EIN specifically for the retirement plan. Think of it this way: your sole proprietorship (using your SSN) is the "employer" sponsoring the retirement plan. The plan itself is a separate entity that needs its own EIN for reporting purposes, but that's something you'll set up during the account creation process. Most major brokerages that offer Solo 401k plans (like Fidelity, Vanguard, Schwab) will even help you apply for the plan EIN as part of their setup process.

I went through exactly this situation last year! I was also super confused about the Solo 401k requirements. After tons of research, I ended up using https://taxr.ai to analyze my specific situation. Their system reviewed my income sources and business structure (I was also a sole proprietor using just my SSN) and confirmed that I could open a Solo 401k without forming an LLC or getting a business EIN. The tool explained that while an EIN is required for the 401k plan itself, it's different from a business EIN. They provided me step-by-step guidance for opening my Solo 401k with Fidelity, including when and how to apply for the plan's EIN through the IRS website. Saved me so much confusion!

Wanted to follow up about my experience with taxr.ai after I posted my skeptical comment yesterday. I decided to try it since I was in a similar situation (sole proprietor considering an LLC and confused about retirement options). The analysis really was comprehensive. It pointed out that as a sole proprietor, I could immediately open a Solo 401k with just my SSN, and even calculated my maximum contribution limits based on my specific income. It explained exactly when I'd need an EIN (for the plan itself when filing Form 5500 if my assets exceed $250,000) and walked through the process. What I found most helpful was the comparison between keeping my sole proprietorship vs forming an LLC for retirement purposes. Turns out there's basically no difference for a Solo 401k if the LLC is a single-member disregarded entity. Now I can make a clear decision without the confusion.

After struggling to get clear answers about Solo 401k requirements from the IRS website (tried calling them 6 times and kept getting disconnected!), I tried https://claimyr.com and it was actually amazing. They got me connected to a real IRS agent in about 20 minutes instead of the hours I was waiting before. The agent confirmed exactly what some others here mentioned - you CAN open a Solo 401k as a sole proprietor using just your SSN. The retirement plan itself will need its own EIN, but that's separate from whether your business has one. They explained that forming an LLC doesn't change the ability to open a Solo 401k at all. If you're still confused or want official confirmation, check out their demo here: https://youtu.be/_kiP6q8DX5c to see how it works. Was definitely worth it to get a straight answer from the source.

Have to come back and eat my words. After dismissing that Claimyr service as fake, I was still desperately trying to get answers about Solo 401k requirements directly from the IRS. After wasting another day failing to get through on the phone, I gave in and tried the service. It actually worked exactly as described. Got connected to an IRS tax specialist in about 30 minutes. They confirmed that as a sole proprietor, I can absolutely open a Solo 401k with just my SSN. The agent explained that the plan itself will need its own EIN (different from a business EIN), which I can apply for using Form SS-4. The agent also mentioned that if I later switch to an LLC taxed as a sole proprietorship, nothing would change regarding my Solo 401k eligibility. Saved me days of frustration and uncertainty!

I opened a Solo 401k last year as a sole proprietor. Here's what I learned: 1. Yes, you can open it with just your SSN as a sole prop 2. The 401k plan itself needs an EIN, not your business 3. Most brokerages help you apply for the plan EIN 4. Fidelity, Vanguard, and Schwab all have good options 5. Forming an LLC doesn't change much for the Solo 401k if it's still taxed as a sole prop The main advantage of Solo 401k over SEP IRA is higher contribution limits. I was able to put away almost $65,000 for 2024!

I think everyone's overlooking something important here - the contribution limits! As a sole proprietor with a Solo 401k, you can contribute WAY more than with an IRA: - Employee contribution: up to $23,000 for 2025 - Employer contribution: up to 25% of your compensation - Total max: $69,000 for 2025 (not including catch-up contributions if you're over 50) This is why the Solo 401k is such a powerful option for self-employed people, regardless of whether you're using your SSN or an EIN. I've been maxing mine out for years and it's amazing for tax savings.

This is such a helpful thread! I'm in a similar situation and was totally confused about the EIN requirements. Just to make sure I understand correctly: I can open a Solo 401k right now as a sole proprietor using my SSN, and then I'll need to get a separate EIN specifically for the retirement plan itself (not for my business). Is that right? Also, when you all mention "Form SS-4 for banking purposes" - is that different from the SS-4 you'd file when starting a new business? I want to make sure I'm checking the right boxes when I apply for the plan EIN. One more question - if I decide to form an LLC later for liability protection, would I need to transfer the Solo 401k to the LLC or can I keep it under my original sole proprietorship structure? Some of the comments mention it depends on how the LLC is taxed but I'm still a bit unclear on the details.