I need to calculate the date of the last day of the month a given date is in. If the date is 8/21/2007, I want the calculation to return 8/31/2007.

I am using a calculated global field listed below.

I get the error message "List usage is not allowed in this calculation" with the closing "]" highlighted.

What am I doing wrong, or is there a better algorithm.

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// To calculate the last day of the month from BLK209 date

Let([

CSODate = g Date BKL209;

CSODay = Day ( g Date BKL209 );

AddDays = If ( CSODay > 15 ; CSODay + 20 ; CSODay + 35 );

NextMonth = getasdate( CSODate + AddDays);

NextYearNo = Year ( NextMonth );

NextMoNo = Month ( NextMonth );

]; // end variable declarations

Date ( Month ( NextMonth ) ; 1 ; Year ( NextMonth ) ) - 1 // Get the first of the next month then subtract 1 day

)

The date of the last day of the month is the day before the first of the next month.

Date( month + 1 ; 0 ; year )

Let(

[

month = Month( g Date BKL209 ) ;

year = Year ( g Date BKL209 )

] ;

Date ( month + 1 ; 0 ; year )

)