To get a deduction for the current tax year, the plan must be established before year's end. Once that's done, actual contributions can be deferred until the extended due date for that year's return. Annual actuarial fees and the required IRS report can run up to a couple grand. If you're younger, go with a SEP or profit-sharing Keogh.
Comments Can be a profit-sharing plan or a defined benefits plan.
Generally requires a professional to set up.