Fund a SEP-IRA or solo 401(k) in a peak-income year
Dec 31 hard stopIn a peak-income year, a self-employed retirement plan is often the single largest deduction available. A solo 401(k) permits both the elective deferral and an employer profit-sharing contribution — more than a SEP at the same income — but the plan must be established by Dec 31 to make the elective deferral, even though funding can follow. The choice between SEP and solo 401(k) turns on income level and timing.
Assumes a solo 401(k): $23,500 elective deferral plus ~20% of net SE earnings as profit-sharing, capped at the $70,000 §415(c) limit — about $48,139 of contribution deductible at a ~24% marginal rate. Deferral, not a permanent saving; the plan must exist by Dec 31.