I think what the real question should be is how do you retain control of franchises and the royalties due when their round grows organically by people recommending them to others. Also the can you justers that want extras done like having their gutters cleared and cleaned etc that happens to go into the franchises back pocket?
It's a good question.
You can have systems in place to keep track of franchisees, and we do. However, IMO the most important thing is to have the right people.
It's easy to (and plenty on this thread have) become fixated on the 20% royalty but it's possible to see it another way. Typically as an employee, you'll get anything from 15% to 30% of what you make for your employer. Our franchisees get 80%. If you have people who see it like that, you're fine.
Am I going to be worried about a gutter, fascia and soffit clean paid in cash going into the guys' pockets occasionally? No, not really (but I'll also add that my advice to them all is not to bother more because of HMRC than for our benefit). Why wouldn't I be bothered? Because this is a long-term relationship and that's the bit that matters. I'd care deeply about the systematic fraud involved in hiding customers (for that is what it would be) because that's affecting the long-term relationship.
I treat franchisees like they are trustworthy adults and, to date, they have all responded by being trustworthy adults.
Vin