All assets to spouse
The deceased leaves all his assets absolutely to his wife. As she was still alive when he died, their children would get nothing from his estate.
The children may decide to claim their legal rights. Between them they can claim one third of the net moveable estate (TSEM6507). If there were two children, and they claimed, each would receive one sixth.
Liferent to spouse
The deceased leaves a liferent of the whole estate to his wife. This creates a trust. She receives the income arising, less trust management expenses. The will states that this is for the rest of her life. It could have been a shorter period, for example, until she re- marries. The estate will go to the children, when she dies.
The widow and her children each have legal rights. She can give up her liferent, and claim one third of the net moveable estate ( TSEM6507). The children can, between them, claim one third of the net moveable estate.
If the widow claims her legal rights, the trustees must decide the date that the children become entitled to their share of the estate. It may be immediately. It may be when the liferent was originally due to finish. It depends on the terms of the will.
If it is the original finishing date, there may be a trust under the doctrine of equitable compensation. The income arising to the remaining estate is accumulated. It fills the ‘hole’ in the estate that the legal rights claim created. Because it is accumulated, it is within ICTA88/S686. The accumulation cannot continue more than 21 years. If the ‘hole’ is not filled by then, there is an even more obscure legal situation.
If you have any doubt or difficulty refer to HMRC Trusts Edinburgh.