Solo 401(k)
For an owner with no employees other than a spouse. You contribute both as the employee and as the business, which is why it usually allows more than an IRA at the same income. Roth contributions are an option in many plans, so some of the money can grow for tax-free withdrawal later.
It asks for a little more paperwork than a SEP and it has to exist before the deadline that applies to your entity, which is why this is a conversation to have during the year, not in April.
