Is it possible to write a conditional format like this?

"If the contents of this cell do not equal the contents of the last
occupied cell in this column, format the cell in a particular way."

I'm building a transaction schedule, dates in the A column, balances in
the F column. As more transactions are added to the schedule, the last
occupied cell in the column changes.

In a cell outside the schedule, I have a check value from another
source that should tie back to the last occupied cell in the row. I
want that cell to have a certain format if there's a discrepancy,
rather than me having to manually check the two figures.

Thanks in advance.