Deciding and stating your position.
THE THREE POSITIONS
You take backups and can restore on request. Most valuable, most work, worth charging for. Clients take their own. Lowest effort, and say so clearly in writing. Both, which is the honest recommendation.
WHAT TO PUT IN WRITING
How often backups run How long they are kept How to request a restore Whether restoring costs anything How quickly it can be done
The ambiguity here is what causes disputes on the worst possible day.
WHAT NOT TO DO
Imply comprehensive backups you are not taking.
That promise surfaces when a client has lost everything.
PRACTICALLY
Per-account backups sending off the server A monthly copy retained for each client A restore tested on one client site quarterly A record of which client has what
WHAT SERVER-LEVEL BACKUPS COVER
Accounts within your reseller allocation, according to your plan's retention.
Check what yours includes rather than assuming, and supplement it.
CHARGING FOR IT
Managed backups with a guaranteed restore is a service. Price it.