Because it allows employee elective deferrals where a SEP plan would not, a solo 401(k) plan would allow at least as much to be contributed as could be contributed to a SEP plan. Whether the additional complications of establishing a solo 401(k) plan rather than a SEP plan would depend on the amount of net earnings, the amount of desire to make retirement contributions and how much tolerance there is for the greater limitations on access to the funds before age 59½. A SIMPLE IRA plan might be a reasonable choice under limited circumstances but comes with some substantial restrictions that might make it not worth the trouble.
