I have a new starter, they will only be working a few hours a week but they have another part time too which is only about 10 hours a week. When I made her a new starter on Moneysoft because I ticked the box that said this wasn't their only job it has given me the tax code BR. I am almost certain this person will earn well below the tax threshold for both jobs so it doesn't seem right that they will be taxed at 20% on the one job. Is this correct or is there something I have missed and not ticked a box or something?
No that is correct. If they have another job then you have ticked the correct box. It is not up to you to worry about the employee's other job. What they should be doing, if they think they will not earn above the threshold in either job, is contacting HMRC and asking them to split their personal allowance between the two jobs. But this is not up to you Although I suppose you could suggest it.