My dad has died and has left everything 50/50 to me and my sibling. However, I know that he gave my sibling a large sum of money before he died. Can this be deducted from my sibling’s share of the estate?

You will need to check the provisions of the Will. The Will might say whether your dad intended to set the amount of gift off against your sibling’s share of their estate.

If your dad intended the sum of money he gave to your sibling as a completely separate gift, then you cannot deduct the sum of money from their share of the estate. However, your sibling will have to prove that this was your dad’s intention when he made the lifetime gifts, as it is presumed that a person would not make the same gift twice (known as the rule against receiving “double portions”).