A 401(k) plan or a SIMPLE IRA plan would allow elective deferrals against which the partnership could (or in the case of a SIMPLE IRA plan, generally must) provide matching contributions. If either of these plans was adopted by the partnership, no contribution would have to be made for any partner that did not make elective deferrals. With only partners in the company and no regular employees, a one-participant 401(k) (a misnomer) could be established which has less involved annual reporting requirements than a 401(k) intended to cover regular employees and would not be subject to anti-discrimination testing.
