In ideal scenarios, there is no reason to increase the price based on the revenue unless working involves increased efforts to a substantial extent. I would quantify the efforts required in hours and get a quote from the freelance consulting accountant. Based on your details, it appears that you do most of the bookkeeping activities and so the consultant has to validate and do Govt formalities. Unless you are doing some specialized business where you will need to defend or work with Govt officials for certain things within accounts, you should be paying charges wrt to the effort involved and yearly inflation rise.