Residence Nil Rate Band Downsizing Addition: How It Works 2026/27

The problem the downsizing addition solves

The residence nil rate band (RNRB) is an extra Inheritance Tax allowance available when a qualifying residence is left to direct descendants (children, grandchildren, and some others) on death. But what if someone sells their home years before they die — to downsize, to move into a care home, or to move in with family — and the family home is no longer part of the estate at death?

Without a special rule, this would mean losing the RNRB entirely, purely because the person no longer owned a qualifying residence at the point of death, even if the proceeds of the sale were still left to their children. The downsizing addition exists to prevent this unfair outcome.

How the downsizing addition works

If someone disposes of a home (by selling it, gifting it, or otherwise ceasing to own it) on or after 8 July 2015, and:

1. They would have been entitled to some or all of the RNRB had they kept the home until death, and
2. They leave other assets of an equivalent value to direct descendants,

then the estate can claim a downsizing addition equal to the RNRB that was "lost" by disposing of the property, up to the value of the assets actually passed to direct descendants.

Worked example: In 2021, Harold sells his £600,000 house and moves into a rented flat, giving the sale proceeds to his savings, which he later leaves entirely to his two children. He dies in 2026. Although he owned no residence at death, because he disposed of a qualifying home after 8 July 2015 and left assets of equivalent or greater value to his children, his estate can claim the downsizing addition — restoring the RNRB (£175,000 in 2026/27) that would otherwise have been lost, provided the total estate does not exceed the tapering threshold.

Why the 8 July 2015 date matters

The date is fixed because that is when the residence nil rate band policy was first announced, even though the allowance itself was only phased in from April 2017 (rising in stages to its current level). Any disposal of a home before 8 July 2015 does not qualify for the downsizing addition — the policy only protects people who downsized in anticipation of, or after, the announcement of the new allowance, not earlier decisions made with no knowledge of it.

Tapering still applies

Even with a successful downsizing addition claim, the combined RNRB (standard plus downsizing addition) still tapers away for larger estates — reduced by £1 for every £2 that the total estate value exceeds £2 million at death. A very large estate can therefore still lose some or all of the benefit of the downsizing addition, exactly as it would lose the ordinary RNRB.

Claiming the downsizing addition

The downsizing addition is not automatic — the personal representatives (executors) must actively claim it as part of the Inheritance Tax account submitted to HMRC, typically using the IHT400 form and its residence nil rate band supplementary pages. The claim must generally be made within two years of the end of the month in which the person died, though HMRC has discretion to allow a late claim in appropriate circumstances.

Executors need to establish and document:

• The date and value of the former residence at the point it was disposed of.
• Confirmation that the disposal was on or after 8 July 2015.
• Evidence that assets of equivalent value passed to direct descendants under the will or intestacy rules.

Why this matters for downsizing decisions

Many people considering downsizing or moving into care worry that selling the family home will cost their children an Inheritance Tax allowance. The downsizing addition is specifically designed to remove that worry — as long as the value that would have been protected is still ultimately passed to direct descendants, the RNRB benefit is not lost purely because of the timing or fact of the sale. This makes downsizing decisions in later life considerably more straightforward from an Inheritance Tax perspective than they might first appear.