I posted in the other thread you posted in, but it could be the provider wants a Performance Surety Bond.. That means he wants added protection from any Losses. I am not sure but your Errors & Omissions MIGHT be what he wants to see.. if not and he's looking for a "GUARANTEE" I would make sure you have an AIRTIGHT contract and/or legal advice, he may be wanting more assurances than you should be given. Protect yourself! Look into your Errors/Omissions if you have it. I recommend that all billing companies have errors and omissions. We live in a world now where anyone can sue anyone for anything.