Calculating Total Project Backlog Per Month

HI  Anonymous 

For your case, you need to add a start date column in your table, like this:

Then try this way as below:

Step1:

Create a dim Calendar table

Eg.

Calendar = CALENDARAUTO()

Step2:

create a monthly project Cost column

monthly project Cost = 'Table'[total project Cost] / (DATEDIFF('Table'[Start Date],'Table'[end date],MONTH)+1)

Step3:

Create a measure as below:

Total = 
VAR tmpCalendar = ADDCOLUMNS('Calendar',"Month",MONTH([Date]),"Year",YEAR([Date]),"MonthYear",VALUE(YEAR([Date]) & FORMAT(MONTH([Date]),"0#")))
VAR tmpBilling = ADDCOLUMNS('Table',"MonthYearBegin",VALUE(YEAR([Start Date]) & FORMAT(MONTH([Start Date]),"0#")),
                                      "MonthYearEnd",VALUE(YEAR([end date]) & FORMAT(MONTH([end date]),"0#")))
VAR tmpTable = 
SELECTCOLUMNS(
    FILTER(
        GENERATE(
            tmpBilling,
            SUMMARIZE(tmpCalendar,[Year],[Month],[MonthYear])
        ),
        [MonthYear] >= [MonthYearBegin] &&
        [MonthYear] <= [MonthYearEnd]
    ),
    "Project",[Project Number ],
    "Year",[Year],
    "Month",[Month],
    "Project Cost",[monthly project Cost]
)
RETURN SUMX(tmpTable,[Project Cost])

Result:

here is a same blog, you could refer to:

https://community.powerbi.com/t5/Quick-Measures-Gallery/Periodic-Billing/m-p/409365

and here is my sample pbix file, please try it.

Regards,

lin