In a purchase voucher, if you provide an invoice number as the reference number, the reference number appears in the invoice-wise listing of the supplier’s balances. This is because the voucher number is used for sequential numbering, whereas the reference number is provided as per the invoices received from the creditors.
In the creditors outstandings report, the reference number is required for reporting, and not the voucher number. In the debtors outstandings report, the invoice number which you had entered, is required for reference. Due to this reason, TallyPrime picks up the voucher number in the debtors outstandings report.
If your sales voucher number starts from 1 (which is automatically set in TallyPrime) and your sales bill number starts from 5001, you can alter the sales voucher type and set the starting number as 5001. Reason being, we consider the sales bill number as reference in the oustandings report of the customers.