The Inheritance Tax residence nil-rate band (RNRB) is a transferable allowance for married couples and civil partners (per person) when their main residence is passed down to a direct descendent such as children or grandchildren after their death. 

The RNRB came into effect on 6 April 2017 and was introduced in stages. The allowance increased to the present maximum level of £175,000 from 6 April 2020. Going forward, the allowance is set to increase in line with the Consumer Price Index. The allowance is available to the deceased person’s children or grandchildren. Any unused portion of the RNRB can be transferred to a surviving spouse or partner. The RNRB is on top of the existing £325,000 Inheritance Tax nil-rate band.

The allowance is available to the deceased person's children or grandchildren. Taken together with the current Inheritance Tax limit of £325,000 this means that married couples and civil partners can pass on property worth up to £1 million free of Inheritance Tax to their direct descendants. 

There is a tapering of the RNRB for estates worth more than £2 million even where the family home is left to direct descendants. The additional threshold will be reduced by £1 for every £2 that the estate is worth more than the £2 million taper threshold. This can result in the full amount of the RNRB being tapered away.