I have already reviewed this thread here, and while it's useful and kind of similar, it's a bit different and I think it deserves its own discussion. This situation is happening in Canada (if it helps) and here is the summary:
I had to consult my accountant for a new business opportunity that I'm exploring and he kindly met me for a two hour meeting and offered 30min phone conversation and probably reviewed some documents for me. In our first meeting I offered to pay the 2-hr thing (around $400, his usual rate, which is a lot for me) and he said:
"Keep the money, once you open your business I will charge you then".
After that I did not offer to pay, but I think I should return the favor to him somehow. I could bake cupcakes or bring him some chocolate or things like this but I don't think he prefers sweets. (And this is all I can offer!)
I think best thing that works for him is if I paid him back, but I don't know how to pop the question in a nice fun casual way in a thank you email.
If it helps, he advised me to not open that business so he really can't charge me later ;-)