Conditional format date based on another date

[Gandarthvader]

Hello, I've found some similar suggestions to my issue, but nothing yet that has solved it. My appologies if I'm just missing something, but I have a table with a 2026 Due Date and 2026 Completion Date column. Both have dates listed. 

I'd like to have cells with a 2026 Due Date that is within the next 30 days to show up with a yellow back ground, or if it the 2026 Due date is past due then give it a light red background; only if the 2026 Completion Date is cell is blank.

But if the 2026 Completion Date is filled out I would like it to ignore the color rules in the 2026 Due Date column and have no background color since it is completed.

The format of the table columns are as follows: 'API Worksafe'[2026 Due Date] and 'API Worksafe'[2026 Completion Date]

I've attached a screenshot of the current table for a visual and marked the 2 columns that I'm working with in this question. 

Thank you for any help!!!

[Gandarthvader]

You are awesome! That worked like a charm. Thank you so much!!

[johnt75 · Accepted solution]

You can use a measure like

Cond formatting = IF(
    ISBLANK( SELECTEDVALUE( 'Table'[Completion Date] ) ),
    VAR CurrentDueDate = SELECTEDVALUE( 'Table'[Due Date] )
    VAR InNext30Days = CurrentDueDate >= TODAY() && CurrentDueDate <= TODAY() + 30
    VAR PastDue = CurrentDueDate < TODAY()
    VAR Result = SWITCH( TRUE(),
        PastDue, "red",
        InNext30Days, "yellow"
    )
    RETURN Result
)

and apply that as conditional formatting for the background for the due date.