"Guaranteed min 10% ROI" can use in ads??

I have no idea what Canadian law might require, nor do I know what problems you might encounter under the law of other countries . But I'll respond generally based on U.S. law. You have this question listed under "investment fraud," but a straightforward business coaching arrangement isn't the sale of a security. Thus, I see no up-front legal impediment to your advertising a guarantee for a 10% increase in some aspect of a client's business or revenue production. However, you'd better not guarantee a result unless you have a contract that clearly spells out the nature of your guarantee, provides a method for determining whether you've performed as promised, spells out your expectations regarding client cooperation, and delineates what you'll do in the event your customer doesn't reach the target. And most important, you need to be prepared financially to make good if your promised results don't occur. If you don't consult with a competent business lawyer to do the necessary planning and document prep prior to launching this endeavor, you'll be asking for lawsuits.

Anyone you $100,000 is likely to take you at your word, and likely to have the assets to pursue you all the way to trial. A ten percent return on investment guaranty is huge, and unless you have a track record and the assets to back up your guaranty, you might not need a big room.

Yes, you can guarantee results. The real question is whether you can deliver on your guarantee? If you don't deliver, you could be sued for breach of contract, breach of warranty and perhaps fraud. Before you make this guarantee, you should spend some time with an attorney to discuss the ramifications and drafting of your contract terms. Good luck with your venture.

There are so many scenarios that come to mind with what you wrote above. My suggestion, find a good barrister that is family with online business or international business so that he/she can draft disclaimers and other fine print statements for you. Further, even if what you say is true, how would the 10% be determined? Net? Gross? Over head? No Overhead? There are times people need to hire attorneys. You are now one of them. I wish you luck with your business. Sounds interesting. If you have a method that you haven't sold, you might want to discuss it with an IP attorney to see if there is anything worth patenting. GOOD LUCK!