5500-SF 9a (Plan Characteristic) Code 2D

When would you use code 2D on line 9a?

I have a 401(k) Profit Sharing Plan where the employer also maintains a cash balance plan. Because the CBP was not PBGC covered in the first year, the 31% rule is applied; accordingly, the 401(a) feature of the 401(k) PSP is capped at 6%. My thought is this sounds exactly like "Plan benefits are subject to offset for retirement benefits provided in another plan or arrangement of the employer", but I've not swam these waters frequently and I'm not able to find any guidance on this code in particular.

No, the 6% and 31% are limits, not offsets.

Suppose you have a plan that defined the benefit as $X minus the value of a benefit provided to the participant under another employer’s plan. That’s an offset.

Gotcha, that makes sense, thank you John!