Assuming that these contributions are to the partnership's retirement plan and that is a type of plan such as a 401(k) that accepts elective deferrals, the code R entries in box 13 of the past year's Schedule's K-1 were done correctly and this year's was not. The code R entry in box 13 should be the total of both employer and employee contributions to the partnership's retirement plan. The only reason I can see to report something retirement account related in box 20 with code AH would be if deposits were made on your behalf for your convenience to a regular personal traditional or Roth IRA, in which case the code AH entry is informational only and the corresponding contributions would be reported on your tax return as regular personal contributions, not contributions to a retirement plan of the partnership.
I suggest contacting the preparer of the Schedule K-1 to obtain a correction.
