Your friend is going to write off your cost as a business expense so you should not worry about how much it is going to cost him. In a way you are doing each other a favor so that cancels out any increase/decrease considerations. Charge him what you think you are worth. If a CPA charges a couple hundred an hour and you are not a CPA then obviously you should fall somewhere below that. There is a difference between what an agency would charge for a contractor to come in and what they actually get paid. Usually its around one third or less. So a good starting point could be around $50 to $66 an hour with an expected limit of how many hours to be worked. That way your friend knows the total spend (give or take 10%). You should have a firm idea of how long it will take. On the other hand, if your friend may keep you on part time to continue to keep his books up to date (since he is likely to be too busy), it can be defined as so many hours per month. If under that arrangement $66 seems too high you can adjust, but really for any kind of accounting/IT (which is also part of what this is) work done like this, $66 is not that high at all. If there is a possibility of the position turning into full-time work, then you can consider what you think the position should pay and charge something near to the hourly (plus benefits) that should be. However, if you have real solid experience (just no cert) then I would go higher, or if you are just good at numbers stuff but not have a lot of experience you may need to go lower to compensate that you will have to learn a few things your self and your friend knows that too.