On the income entry screen you can specify that you want to print a receipt at the time of creating the transaction.
In the coming version, you will also be able to print the receipt after the transaction is complete. On the income entry screen the Print Receipt checkbox will be replaced with a Reprint Receipt button.
Note that on a reprint, the 'Current Balance', 'Paid To Date', and 'Previous Paid To Date' fields will all print as blank. So if you use any of those fields on your receipt, you should always try to print them the first time instead of going back to a reprint. The reason is because we do not record those values at the time of the original transaction, so there is no way of accurately reprinting it maybe 6 months later.