Hi.It will only be a problem if the tax office ask you to give your reasoning behind a valuation of £10,000 but that doesn't justify what could be a spurious attempt to get some tax free cash. I'm also wondering how a one man building business can have any goodwill since he is the business. Even if he had a list of regular customers, who is he going to sell the list to? I might give regular work to your client because he does a good job but if he sells my name to another builder, I won't necessarily use the new one for building work. It might be different if he has contracts with local authorities or other businesses.You have to be able to justify a valuation of goodwill if you are asked to by the tax office.I hope this helps but let me know if you have any further questions.