Short plan year w/ self employed--comp issue

As I understand it, sole proprietors and partners are considered to have their income determined on the last day of the year.

How does that work in a short plan year?  I have two examples:

1)  Plan year 10/1/21 to 12/31/21.  Effective date 10/1/21.  Does everyone use pretty much 1/4 of their comp, but the owner gets to use all of it (subject to the comp limit and 415 limits) because it was all "earned" on 12/31?

2)  Plan year 1/1/21 to 6/30.  Everyone gets comp for first half of year, 415 and comp limit are pro-rated.  But Partners get zero comp, therefore zero benefit because they earn their comp 6 months later?

Always double-check the Plan's limitation year definition before pro-rating.

1.  Yes, actual compensation between 10/1 - 12/31; on a basic level, the owner(s) would have theirs applied up to the applicable compensation limit including any pro-ration.  Alternatively, the Plan Administrator could "spread" the owner(s) compensation over the year based on their level of service (IRS uses service to justify the regular, year-long deposit of deferrals for owners) and recognize that portion for service from 10/1 - 12/31.

2.  A half-year determination of compensation would have to be performed as of 6/30, and deemed acceptable by the Plan Administrator.