Month select without picker

Hi there!
i need to set a date based on today`s date, minus one month, (e.g. report executed on 12/03/19 posting dates should be 11/1/2019 to 11/30/2019) but there is no calendar to picking, can anyone help me please ? thank you!!!

Hope this expression would help you resolve this
(DateTime.ParseExact(“11/01/2019 00:00:00”, “MM/dd/yyyy hh:mm:ss”,System.Globalization.CultureInfo.InvariantCulture)-DateTime.Now).Months.ToString

This will give the difference of the month between the values