Not without adding an extra field. Here's one method:
Define a calculation field, cMonth as:
YourDateField - Day ( YourDateFIeld ) + 1
Be sure to select Date as the calculation field's return type. This calculation returns the date for the first day of the month of the same month and year as the date in YourDateField.
Now you can sort your records by cMonth and set up a sub summary layout part "when sorted by cMonth" to get your sub totals with a summary field placed in this added layout part. There are also several other methods for getting the sub totals
Ps, the Format of the date makes no difference, but it is vital that YourDateField be of TYPE date.
will try, thanks so much
Perfect, thank you.