The nil-rate band is the value of your estate that is not chargeable to IHT. The amount is set by the government and is currently £325,000 which is frozen until April 2031. The nil-rate band does not apply to spouses and civil partners as they are exempt from paying inheritance tax on the estates of their significant others. This is also true of other qualifying beneficiaries, such as charities.
In addition, if you leave your home to direct lineal descendants which includes amongst others your children (adopted, fostered and stepchildren) and grandchildren. The value of your estate before tax is paid, will increase with the addition of the residence nil-rate band. The residence nil-rate band is set at £175,000.