Once deemed a tax for the wealthy, the IHT net is catching more people than ever before. Generally, each individual has an IHT allowance of £325,000 (less any lifetime gifts made in the seven years before death) which they can leave on death before IHT is paid at 40%. The £325,000 is transferrable on first death to any surviving spouse / civil partner if the estate is left to them on death.
Broadly speaking, the RNRB is available if you leave your main residence to your children or grandchildren (and a few other specific beneficiaries, limited to descendants) and your estate is worth under £2m at death. The RNRB is not available if you do not have children.
The RNRB gives you an additional £175,000 which again is transferrable to a spouse / civil partner on first death if the estate is left to them on death.
There are a number of planning options (but care should be taken together with appropriate advice about anti-avoidance rules):-
The Lawyer in London