Adapting the examples for creating a 2 digit year, month, day + "-" and number I have ended up with the below, which is now working:
Me.txtq_id = Format(Me.txtq_date_created, "YY") & Format(Me.txtq_date_created, "MM") & Format(Nz(DLookup("CountOfQuotes", "qryQuoteCount", "Quotes= " &...