There are two ways they can do this:

1) If Client Login is enabled, then your Clients can log into their Client dashboard and view & pay their Invoice/Credit Request from there - they simply need to click the green ‘Pay Now’ button next to an Invoice found on the ‘Unpaid Invoices & Credit Requests’ panel.

An example of a Client dashboard, with the ‘Unpaid Invoices & Credit Requests’ panel highlighted.

2) They can also pay their Invoice/Credit Request without logging in via the secure payment link found on any payment request emails sent to them - this will take them to the secure Invoice payment portal.

In both cases, the Client will first be presented with a number of payment methods that they can choose from; such as Card, Bank Transfer, or Direct Debit. This page will look something like this.

Invoice payment page shown to Clients.

You, as an Admin, have the option to take payments from your Clients through Online or Offline means.

Invoice payment page shown to Admins.

Yes - if you have ‘Automatically mark Invoices paid’ enabled in your General Accounting Settings, you can navigate to the Invoice and select the Pay From Credit button to make a full or partial payment of the Invoice from the Client’s pre-existing credit.

In this case, any credit that the Client has will be deducted from the Invoice as a partial payment, and the remainder will be reflected in the ‘Still to pay’ section of the Invoice.

In the inverse situation, where a Client has more credit on their account than the Invoice total, the remaining credit will remain on their Client balance as part of their Invoice balance.

Find out more about auto charging your clients here.