You should let HMRC know about your partner and tell them how it happened. Usually, if any of our clients are in such a situation, we will advise you to let HMRC know beforehand to save time. HMRC may allow your partner to agree with the tax figures instead of opening a new investigation. Every case has its characteristics and will be judged on its own merits. If you are in a situation where you are unable to draw a line where to start, call our office for a free evaluation of your case.