An argument of function date error

Hi jdb2313,

May I know whether you still have problem on it? If it still exists, please take these official documents as reference to check your arguments.

DATE function (DAX) - DAX | Microsoft Docs

YEAR function (DAX) - DAX | Microsoft Docs

MONTH function (DAX) - DAX | Microsoft Docs

DAY function (DAX) - DAX | Microsoft Docs

And check your fields’ data types in its Formatting section to make sure they are qualified.

For it’s a long DAX formula. Here is a website that can help you format your DAX formula for better reading. DAX Formatter by SQLBI

And for there are many duplicated code segment in your formula, I would recommend you using variable in it, which will help you simplify the formula and accelerate the calculation.

Use variables to improve your DAX formulas - DAX | Microsoft Docs

Then, the dax should look like this.

Rolling4QtrMin =
VAR bool =
    DAY ( [MaxDate] ) = 29
        && MONTH ( [MaxDate] ) = 2
VAR trueVal =
    DATE ( YEAR ( [MaxDate] ) - 1, 2, 28 ) + 1
VAR falseVal =
    DATE ( YEAR ( [maxDate] ) - 1, MONTH ( [MaxDate] ), DAY ( [MaxDate] ) ) + 1
RETURN
    IF (
        DAY ( IF ( bool, trueVal, falseVal ) ) = 29
            && MONTH ( IF ( bool, trueVal, falseVal ) ) = 2,
        DATE ( YEAR ( [MaxDate] ) - 1, 2, 1 ),
        IF ( bool, trueVal, falseVal )
    )

If there is any post helps, then please consider Accept it as the solution to help the other members find it more quickly. If I misunderstand your needs or you still have problems on it, please feel free to let me know. Thanks a lot!

Best Regards,

Community Support Team _ Caiyun