In a 401(k) Plan covering employees and persons who are partners, (i) are partners eligible to make catch-up contributions (i.e., are they considered to make "elective deferrals" where in fact they 100% pay their own contributions to the plan, in whole or in part, by writing a check to the plan no later than 4/15 following the close of the plan year in issue), and (ii) if the answer to (i) is yes, then can these partners pay in their catch up contribution along with their regular plan contribution by writing a check to the plan for that amount prior to 4/15 following close of the plan year (assuming that they made an irrevocable election to do so on or before 12/31 of the plan year)?

See thread under self employed person contribution to 401(k) plan under this topic. last comment 1/16. Since partnership is deemed to earn all of its income on 12/31, partners can make contribution from annual draw provided that they have executed a salary reduction agreement by 12/31. When pship determines each partners draw the pship makes a contribution to the plan from the draw due each partner. Since the catch up is $1000 over the max deferral by each partner, catch up is deferred until the draw is determined and is contributed in the same way. I dont understand why partners would write a check to the plan from personal accounts which is not compensation.