If your suppliers offer an early payment discount you can easily account for it in Tally.  Firstly you need to set up an Outgoing type called ‘Early payment discount’.  Do this by going to the Purchases Tab and clicking Add new Purchase Type in the top right had corner.  After you have done this you will need to create a new receipt for the supplier, add a line item which uses the outgoing type you’ve just created.  This item will have a negative value to the amount of the discount.  If you then go to the receipt you wish to apply the discount to you will have the option to use the receipt you have just created as part payment for the invoice thus acting as a discount.  After you have paid the amount less the discount and applied the discount as above, both receipts will be marked as paid.