Modification of DAX for Aging Calculation Based on Selected Month

Thank you InsightSeeker for sharing the sample data with me.  

I have a couple of observations.  

1) Your 'Calendar Ultimate' table doesn't cover the entire period of the invoice date, and because of this, not all the data in fact table is slicerable from 'Calendar Ultimate' table.  In order to counter this issue, I've created a calculated calendar table which covers all the period of the invoice dates.  

2) Another observation about your data is that your 'Data' only contains the Invoice information only and not the cash collection.  In fact, the construct of the AR balance is "Invoice recording minus cash collection" for the balance sheet. So unlike the P&L sales amounts which just accumulates over the year to date period, the balance of the balance sheet accounts receivable is the cumulative total from the inception adding the invoice and subtracting the cash collection.  Without the cash collection information, you cannot say if the invoice is still outstanding or cleard by the cash collection at any particular point in time.  Because of this, from your sample data we will just be able to see invoice ageing at particular point in time without incorporating the 2nd part of the story if that invoice is still outstanding at that particular point in time to begin with.  Or are those invocie still outstanding and not collected yet? 

I will carry on with the 2nd assumption, but I'd like to check with you these points first.  

Best regards,