Which retirement plan lets a self-employed person save the most money?

For very high earners, a Solo 401(k) usually beats a SEP-IRA because the employee deferral plus the 25%-of-comp employer contribution stack up faster. But if you earn a large, stable profit and want to shelter even more, a defined-benefit or cash-balance plan can allow six-figure annual contributions, since limits are based on funding a future pension rather than a flat cap. These plans require an actuary and mandatory annual funding, so they suit consistent high income. A common power move is pairing a cash-balance plan with a Solo 401(k). The IRS sets these limits annually. Model the trade-offs with the Retirement Planner at wealthserene.com/tools/retirement-planner and confirm specifics with an actuary or CPA.