A £3,000,000 estate is above the £2,000,000 mark where the residence nil-rate band starts to taper away — it falls by £1 for every £2 the estate is over that line. That shrinks the allowance just as the estate grows, so the effective tax rate on this size of estate climbs. Even a couple combining everything pays £940,000 here.
The £175,000 residence nil-rate band only applies when a qualifying home goes to direct descendants. Without it, a single person's allowance drops to £325,000.
Spouses and civil partners pass unused allowance to each other, lifting the combined headroom to £1,000,000.
Gifts made within seven years of death can use up the nil-rate band first, increasing the tax on what remains.
Leaving 10% or more of the net estate to charity cuts the 40% rate to 36% on the rest.
Most unused pension funds join the taxable estate from 6 April 2027, which can push a £3,000,000 estate into a higher tax figure.