SEP: Less maintenance

“These accounts are popular with freelancers for a reason,”  D'Agnese and Kiernan write. “They're so easy to open that you can do it online in a few minutes.”

Indeed, there's much less paperwork involved with the SEP than there is with the 401(k). Of course, a little paperwork shouldn't keep you from making the most out of your money, but if I've already decided on the SEP, this is icing.

401(k): Substantial, recurring payments

Also, Fidelity explained to me that with the 401(k), you have to make “substantial, recurring” payments - IRS's words, not theirs. I'm not entirely clear on this, but because this is a qualified plan, the account must meet requirements of the IRS code, and two of those requirements are that the payments must be substantial and recurring.

Thus, if you're not contributing regularly to this account, there's a chance that the IRS can  tax and penalize you.

With the SEP, it's up to you when and how much you want to contribute. Another administrative responsibility of the Solo 401(k)? If your plan assets exceed $250,000, you're required to file IRS Form 5500 annually.

Bottom line: there seems to be considerably less maintenance and administrative work with the SEP-IRA.

401(k): Hidden fees?

D'Agnese and Kiernan call the SEP “dirt cheap,” and the Wall Street Journal has reported:

“Solo 401(k)s do in some cases have higher administration fees than SEP IRAs or other plans. Investors need to weigh whether they save aggressively enough to justify those fees.”

Combine this with all of the recent attention on hidden 401(k) fees, and the SEP is an even more attractive option.

There are some additional details that don't apply to me, but I think they're still worth noting. The 401(k) has a loan option, for instance. And with the SEP, “the minute you hire an employee, you must contribute the same amount of money to that employee's SEP as you're paying into your own,” write D'Agnese and Kiernan. They add that, with the Solo 401(k), once you hire employees, the plan is no longer solo and “you must expand your plan to offer your employees the same benefits you're enjoying.”