Dynamics NAV does not have a standard report that will show the Average Days to Pay. To see this information you can navigate to the Customer Card and in the ribbon click Entry Statistics.
The Entry Statistics view has 2 FastTabs. The first one is Last Documents FastTab. This displays the most recently posted entry (in the currency of the transaction) of the following types:
Finance Charge Memo
The second FastTab shows the number of documents. The No. of Documents FastTab displays the number of entries of each of the document types for the current accounting period, current year-to-date, and preceding year.
To see different periods, change the work date and the month from the work date will be the current period.
At the bottom of the No. of Documents FastTab, NAV calculates the Average Collection Period for each period.
The Average Collection Period is determined by subtracting the posting dates from the corresponding payment dates and dividing the total by the number of invoices. The customer's largest balance ($) in each of the three periods is also shown in the Customer Entry Statistics Window.