DAX - POWER PIVOT measures using date before date

Hi PaulStokes possible solution as following

create 3 different calculated columns as you are calculating amounts based on row level

Creation order is important to avoid complexity. Output below is the same as your picture

1. EarlyDate

=
VAR __part=MyTable[PART]
VAR __sup_name=MyTable[SUP_NAME]
VAR __date=MyTable[DATE]
RETURN
CALCULATE(
MAX(MyTable[DATE]);
FILTER(MyTable;MyTable[PART]=__part && MyTable[SUP_NAME]=__sup_name && MyTable[DATE]<__date)
)

2. EarlyValue

=VAR __part=MyTable[PART]
VAR __sup_name=MyTable[SUP_NAME]
VAR __date_early=MyTable[EarlyDate]
RETURN
CALCULATE(
SUM(MyTable[Cost]);
FILTER(MyTable;MyTable[PART]=__part && MyTable[SUP_NAME]=__sup_name && MyTable[DATE]=__date_early)
)

3.% Change

=
IF(MyTable[EarlyValue]=BLANK();BLANK();
MyTable[Cost]/MyTable[EarlyValue]-1)

WOW ! BIG Kudos to some_bih for the reply and answer to my question. Resolved 🙂