Short Answer – If you sell your house, or swap it for a smaller house or gift it away before you pass away, you do not lose your residential nil rate band. You can claim IHT relief for the full value of the house (capped at £175,000) for yourself AND your predeceased spouse, even if you no longer own the house. It is often overlooked and it’s very valuable – it’s also quite an abstract idea and the rules (below) are detailed. But it’s worth investigating if you or the deceased sell there house before they die, and downsize. In the example below, forgetting the relief increases the IHT bill by 85%.
Inheritance Tax Downsizing Relief: Save £100,000+ on IHT – With and Without RNRB Example (2026 Guide)
Table of Contents
Inheritance Tax Downsizing Relief Explained – With vs Without RNRB Calculation 2026
Worried that downsizing your family home will cost your family tens of thousands in extra Inheritance Tax? Inheritance Tax downsizing relief (the RNRB downsizing addition) lets you keep the full £175,000 Residence Nil-Rate Band (RNRB) per person even after selling or moving to a smaller property.
This guide uses a verified real-world example (£550,000 death estate + £450,000 failed PET) to show the exact difference in IHT with and without downsizing relief.
What Is Inheritance Tax Downsizing Relief?
The downsizing addition, introduced in 2017, protects the RNRB when you sell, gift, or downsize your home on or after 8 July 2015. Without it, moving to a smaller house, renting, or entering care could slash or eliminate the valuable £175,000 RNRB (frozen until at least 2028).
Key eligibility:
- Downsizing or disposal on/after 8 July 2015
- Former home would have qualified for RNRB
- Assets left to direct descendants (children/grandchildren)
- Claimed by executors on IHT435
Real Example: IHT With Downsizing Relief vs Without
Scenario details:
- Total Death Estate: £550,000 cash
- Failed PET of the house: £450,000 after five years gets 32% taper relief
- Combined value: £1,000,000
- Total NRB available: £406,250 (£325,000 plus 25% from the previous spouse as a transferable element)
- Maximum RNRB: £350,000 (for couple, or £175,000 each)
Detailed Comparison Table* See footnote!
| Description | With Downsizing Relief | Without Downsizing Relief | Difference |
|---|---|---|---|
| Total Estate Value | £1,000,000 | £1,000,000 | – |
| Total NRB | £406,250 | £406,250 | – |
| Total RNRB (including downsizing additions) | £350,000 i.e. two £175,000 with relief | £150,000 (reduced – only current lower-value home, with no relief by mistake) | £200,000 |
| PET Taxable Amount | £43,750 (£450,000 PET – 406250 NRB) | £43,750 (£450,000 PET – 406250 NRB) | +£0 |
| IHT on PET (32% taper) | £14,720 | £14,720 | +£0 |
| Estate Taxable Amount | £1,000,000 – £450,000 PET – £350,000 2 x RNRBs =£200,000 | £1,000,000 – £450,000 PET – £150,000 (because we forgot downsizing relief) = £400,000 | +£200,000 |
| IHT on Estate (40%) | 40% of £243,750 = £80,000 | 40% of £443,750 = £160,000 | +£80,000 extra IHT by mistake(!!) |
| Grand Total IHT Payable | £94,720 | £174,720 | as above – lots of extra IHT |
| Effective Tax Rate | make this 100% | this is 184% | 84% extra tax… – i.e. lots! |
Note: The “without” scenario assumes a reduced RNRB of £150,000 (common when only a lower-value replacement home remains and no full downsizing addition is claimed).
In the with relief case, the full £350,000 RNRB (standard + downsizing addition) is applied, significantly reducing the taxable portions of both the PET and the estate.
How Downsizing Relief Is Calculated (Step-by-Step)
- Calculate the “lost relievable amount” on the former higher-value home.
- Determine the RNRB used by any current home in the estate.
- Subtract to find the downsizing addition (capped at £175,000 per person).
- Apply the addition only to the extent that equivalent value passes to direct descendants.
- Combine with standard NRB and apply to the estate (after NRB but before final tax).
Executors must keep records of the former home’s value and sale date.
Why This Relief Matters in 2026
With the NRB frozen at £325,000 and RNRB at £175,000 until 2028, more estates face 40% IHT. Downsizing is popular in retirement, yet many families unknowingly lose the extra band.
Common queries answered:
- Can I claim RNRB if I no longer own a home? Yes, via downsizing addition.
- Does it apply if I rent or live in care? Yes, if conditions are met.
- What records do I need? Sale date, value of former home, and proof of proceeds going to descendants.
Planning Tips to Maximise Savings
- Downsize on or after 8 July 2015 where possible.
- Leave sufficient assets (not just the current home) to direct descendants.
- Maintain clear documentation for executors.
- Use a dynamic IHT spreadsheet with blue input cells to model scenarios.
- Review Wills regularly and consider transferable bands for couples.
- Seek specialist advice — claiming errors can be costly.
Frequently Asked Questions
Q: How much can downsizing relief save?
Depending on your circumstances, a huge amount – see below
Q: Is the relief automatic?
No. Executors must actively claim it. If you don’t claim it you don’t get it.
Q: What if my estate is over £2 million?
RNRB tapers away (£1 lost for every £2 over £2m), but downsizing addition still interacts with remaining band.
Q: Does it work with failed PETs?
Yes — reliefs apply across the combined chargeable transfers, as shown in the table.
Final Thoughts
Work through this example, if you’re still uncertain.
The Husband dies in 2017 and the Widow inherits their jointly owned house (his share was worth £175,000 – total house value £325,000) and cash (his share cash). worth £325,000, total value £650,000. The Husband’s estate has No IHT to pay as the surviving spouse is exempt.
The surviving spouse sells the house and briefly lives in a rented house, and passes away later on, leaving £1 million in total. The Widow’s estate could claim 2 rnrbs (£325,000) on the house and two nrbs £650,000 on the cash– meaning NO IHT is due – the total relief is £1,000,000 – the same value as the Widow’s estate.
Clearly this is an example engineered to make a point as the estate value exactly matches the nil rate bands. BUT after 2015, if you sell your house and buy a smaller one, or simply rent, the affect of the downsizing relief is immense – it must not be overlooked.
If you forget to claim downsizing relief on death and pay IHT which is not due, how long have you got to correct the mistake?
The estate’s personal representatives (executors) must make the claim within 2 years of the end of the month that the person died. After which HMRC is not obliged to refund the overpaid tax. HMRC has discretion to accept a late claim in some circumstances (they sometimes do e.g. serious illness or capacity issues, especially with a reasonable explanation and if the estate is still open or overpaid tax can be clearly shown)
Start planning today: update your records, review your Will, and model your own numbers with a flexible calculator.
Useful links
- Footnote – Checked these figures several times by hand – but feel free to correct me if I’m wrong!
How Much Do Solicitors Cost in 2026? UK Legal Fees Explained
Luxury Watches Crypto Money Laundering: AML Risks & UK 2026 Regulations for Conveyancers