For your convenience, you may add a Memo to a payment.

Memo - This option is only available for check payments.  The information entered in the memo section will be printed on the check for your payee to view.  Electronic payments may not have a memo.  You may only add a memo to a payment that has not already been sent to the payee.  A memo may be added to a single payment or to all payments for a payee.

Once a payment has been scheduled you may add a Memo by clicking on the Edit link.  This link will appear to the right of the pending payment.  A smaller window will come up on your screen.  Here is an example:

You will see a memo field for check payments only.  Add your Memo which will appear on the check, and click on the Save button. You should see a confirmation like the one below confirming the changes have been saved.

Please keep in mind that if you add a memo, the memo will appear on all future checks to this payee unless you go through these steps again and delete the memo.