理论上是这样，但实际上不是

if you are self employed you can contribute 20% of your net income (up to the limit). For example, if you have $200,000 income. you can contribute to $40,000 into your SEP IRA. However, you have to pay a lot of employment tax.
You can have a s-corp to save some employment tax. The S-corp pays you salary $60000 annually. If you have a solo 401k, the maximum contribution will be $18500 + 25% of $60000=$33,500