RNRB & Inheritance Tax Calculator (UK)
Estimate your potential Residence Nil Rate Band (RNRB), total tax-free allowances, and a simple inheritance tax projection.
Assumes current headline bands: NRB £325,000, RNRB £175,000, taper above £2m, tax rate 40%.
What is an RNRB calculator?
An rnrb calculator helps estimate how much of your estate may qualify for the UK Residence Nil Rate Band (RNRB), and how that interacts with the standard Nil Rate Band (NRB) for inheritance tax (IHT). In plain English: it estimates how much may pass tax-free before 40% inheritance tax applies.
For many families, the RNRB is the difference between a manageable tax bill and a very large one. But the rules are technical: your estate value, who inherits the home, and whether a spouse's unused allowances can be transferred all affect the result.
Quick refresher: NRB vs RNRB
- Standard Nil Rate Band (NRB): typically £325,000 per person.
- Residence Nil Rate Band (RNRB): typically up to £175,000 per person, only when a qualifying residence is left to direct descendants.
- Transferability: if a spouse or civil partner died with unused allowance, up to 100% of their unused NRB and/or RNRB may be transferred.
- Taper: RNRB is reduced when the estate exceeds £2 million (reduced by £1 for every £2 over the threshold).
How this rnrb calculator works
1) Work out a net estate for taper purposes
The calculator starts with your gross estate and subtracts debts/liabilities. This gives a net figure used to test whether the RNRB taper applies.
2) Determine standard NRB
The tool applies the standard £325,000 and adds any transferable percentage from a late spouse/civil partner.
3) Determine RNRB
The tool starts with £175,000 (plus transferable percentage), then applies two important limits:
- RNRB is only available if a qualifying home passes to direct descendants.
- RNRB cannot exceed the value of the qualifying residence inherited.
4) Apply taper reduction if estate exceeds £2 million
If net estate exceeds £2,000,000, the calculator reduces available RNRB by half of the excess above £2 million.
5) Estimate taxable estate and IHT
Charitable gifts are treated as exempt in this simplified model. The calculator then subtracts available allowances and applies a 40% headline rate to the remaining taxable amount.
Inputs explained (so you can avoid bad estimates)
Gross estate value
Include property, cash, investments, business interests, and valuable personal assets. This should be your broad total before deductions.
Debts and liabilities
Mortgage balances, qualifying debts, and other deductible liabilities can reduce the estate for this estimate.
Value of qualifying home passed to descendants
This is not simply your home's market value; use the portion that will actually pass to direct descendants and qualifies under RNRB rules.
Transferable percentages
These percentages represent unused allowance from a late spouse/civil partner. If none is transferable, use 0%. If fully unused and transferable, use 100%.
Example scenarios
Example A: Estate below taper threshold
A widowed person leaves an estate of £1.2m with a £450k home to children. No liabilities, no charity gifts, and no transferable allowances. They may have up to £500k total allowances (£325k NRB + £175k RNRB), with tax on the remainder.
Example B: Estate over £2m
At £2.4m net estate, RNRB taper is significant: excess is £400k, so RNRB is reduced by £200k. For one person, this usually wipes out the £175k RNRB entirely. Transferable RNRB may still partly help in larger combined estates, depending on values and eligibility.
Example C: Home not passing to direct descendants
If no qualifying residence is inherited by direct descendants, RNRB can be zero even with a high-value estate. In that case, only NRB (and any transferable NRB) applies in this simplified estimate.
Common mistakes people make
- Assuming RNRB applies automatically just because they own a home.
- Forgetting taper above £2m net estate.
- Using full home value even when only part qualifies for direct descendants.
- Ignoring transferable allowances from a late spouse/civil partner.
- Treating online estimates as legal or tax advice without review.
Planning checklist
- Keep wills up to date and aligned with your intended beneficiaries.
- Document historic estate planning and any trust structures clearly.
- Keep records for spouse/civil partner estate use to support transfer claims.
- Review estate values regularly, especially near the £2m taper line.
- Take professional advice for complex estates, trusts, business assets, or foreign property.
Important assumptions
This rnrb calculator is a practical estimator, not a substitute for HMRC guidance or regulated advice. It uses standard headline rates and a simplified approach. It does not model every relief or rule (for example, reduced 36% rates in specific charitable scenarios, business relief nuances, agricultural relief, lifetime gifting interactions, or trust-specific outcomes).
FAQ
Is this a full inheritance tax return calculation?
No. It is an educational estimate designed to give a quick planning view.
Can RNRB be more than the home value inherited by children?
No. RNRB is capped by the value of the qualifying residence that passes to direct descendants.
Does every estate get RNRB?
No. The residence must qualify, pass correctly, and the allowance can be tapered away for larger estates.
Should I rely on this number for legal decisions?
Use it as a starting point only. For binding planning decisions, speak to a qualified solicitor or tax adviser.