It is all well and good but i would rather collect my payment for the work i have done, all you are doing is allowing the customer 12 months free credit.
Then in 12 months who knows what their position is, maybe they will be moving or replacing and not require your services.
Also have you considered that techincally you are offering credit terms and this has other implications, registration with the fisa etc.
Maintainance plans for commercial jobs works where you are cleaning a certain amount per month for a fixed price, maybe more pit falls with domestic.
I dont want to put the idea down because in theory its a good idea, just dont get hit where it hurts most, smack bang in the wallet.
John
P.s I already know my spelling is awful!