Salary paid to wife

That isn't a problem to solve, it's a question to answer. "Is this guy declaring all his taxable profit?". The simple inspection seeks to discover merely whether suspicion is justified that he might not be doing. If they think it is, they will then investigate until they find the truth.

Problems don't have answers. They have solutions.

That's right. But because you might lie, your anwers won't necessraily help them discover truth.

They are part of the process of assuaging or reinforcing their suspicions as to whether there might be something *to* discover.

There is good pedantry and bad pedantry, yours is an example of the latter. It is not customary to say "I have investigated" unless one has finished and come to a conclusion. Otherwise one would say "I am [still] investigating".

I know what you'll say next. The conclusion might be that more investigation is required. :-(

Unless of course you have cause to think they may think you have done something wrong.

A few years ago I was working for an extended period on-site and my client had a payroll inspection in which they had to declare that I was being paid as a contractor. 6 months later I had a call for a 'routine' inspection. Two turned up (there is just myself and wife in my business) and they had not crossed the mat before they asked if I knew about 'IR40' Well I was prepared because my client had told me what had happened but there was no way this was 'routine' and I was minded to make a fuss about it but chickened out