If someone dies on or after 6 April 2017 and their estate is above the IHT threshold, the estate may be entitled to an additional threshold known as the residence nil rate band (RNRB).

The maximum amount of the additional threshold for 2017 to 2018 is £100,000 or the value of the home if this is less. To qualify, the person who died must have left their home, or a share of it, to their direct descendants.

The estate may also qualify if the person downsized, or sold or gave away, their home after 7 July 2015.

HMRC says there is an online calculator to help work out how much additional threshold the estate may be entitled to. This will be the lower of the value of the home, or share the direct descendants inherit, or the maximum additional threshold available when the person died.

If an estate is valued at more than £2m, the amount the estate is entitled to be reduced or tapered away by £1 for every £2 over £2m.

HMRC says taxpayers can apply the additional threshold against the whole value of the estate not just the value of the home and add to this any unused additional threshold from a spouse or civil partner.

If the person who died was married or in a civil partnership and their partner died before them (even if this was before 6 April 2017) there may be some unused basic and additional threshold to use, which the estate can claim.

In the same way, if an estate has not used all the additional threshold, anything left over can be transferred to any surviving spouse or civil partner of the person who has died.

If the first of the couple died before 6 April 2017 it is possible to transfer 100% of the additional threshold or the value of the house if this was less.

Only one home will qualify for the additional threshold. If the person who died owned and lived in more than one home, the executor or administrator can choose which one to use.

If the person who died did not own a home because they had sold or given it away after 7 July 2015, the estate may be able to claim an additional threshold called a downsizing addition.

Similarly, if they had downsized to a less valuable home below the maximum threshold after 7 July 2015, the estate may also be able to claim a downsizing addition.

If the home, or the share of the home, was held in a trust before the person died or is transferred to a trust when they die, it may be possible to claim depending on the type of trust.

HMRC guidance: Check if you can get an additional Inheritance Tax threshold is here.