The portion of guaranteed payments representing payment for services rendered if you are a limited partner or the entire amount of guaranteed payments if you are a general partner is required to be reported with code A in box 14 as well as in box 4. The amount of guaranteed payments reported with code A in box 14 is subject to self-employment tax.
https://www.irs.gov/faqs/small-business-self-employed-other-business/entities/entities-1
The 401(k) contribution is required to be shown with code R in box 13. The code A amount in box 14 is used in determining the amount that you are permitted to contribute to the 401(k). The fact that the amount was a lump sum deposit into the partnership's 401(k) plan has no bearing on the reporting requirement.
