To mark someone as having paid offline for a bill, subscription or shop item, go to the ‘Payments’ tab in your management toolbar.
Click ‘Track Payments’. underneath one of the payments (you may need to click 'view all...' underneath the payment totals first).
Select the members who have paid offline, click on the ‘More Actions’ drop-down menu and select ‘Mark as paid offline’.
The selected members will now be shown under the ‘Paid’ list as paid offline. The amount will also be added to the totals on the 'Manage Payments' page.
N.B. You can also select members of your group who have not been specifically sent a payment request from the 'Not notified' list, and use the 'More Actions' drop-down menu to mark them as 'Paid Offline'.