You can add your Universal pay link to your Invoice Details.

Start by logging in to your FreeAgent account, and go to create or edit an invoice. In the invoice details screen, you should be able to select Set default Additional Text.

A text box will appear. Type in what you want to appear on each of your invoices along with your Universal pay link. Something like this:

Once you've finished typing, select Save to keep the text or Cancel to close without saving it.

If you select Save you'll see that the default text then appears in the Additional Text box. This text will now appear on all of your invoice templates - so you won’t need to add your pay link to every invoice.