I have a client who is registered self employed and they have been offered and accepted a job as an employee, they will continue with their self employed work. They have been given a p46 to complete and have asked me which box a, b, or c should they tick. I think it is c as they do have another job albeit not employed. Am I right
In my opinion you are right, as they do have another job. This will make their tax code a BR for their employed work and then receive their full tax code for their self employed work.
If your client finds as they go that they would rather have their tax code with their employed work (especially if the self employment isn't making enough to cover their full code) then that can easily be changed by getting in touch with the tax office.