Calculate the available RNRB for UK Inheritance Tax purposes (2024/25 Tax Year)
£
£
%
Yes (Children, Grandchildren, etc.)
No
Standard RNRB (Current):£175,000.00
Transferred RNRB Amount:£0.00
Total Potential RNRB:£0.00
Taper Reduction (Estate > £2M):-£0.00
Residence Cap (Home Value):£0.00
Final Claimable RNRB:£0.00
* The RNRB is £0 because the property is not being left to direct descendants.
Understanding the Transferable Residence Nil Rate Band
Inheritance Tax (IHT) in the UK can be complex, but the Residence Nil Rate Band (RNRB) offers a significant allowance for families passing on their main home. This calculator helps you estimate the additional tax-free threshold available when a surviving spouse dies, known as the Transferable Residence Nil Rate Band.
How the Calculation Works
The standard RNRB for the current tax year (2024/25) is frozen at £175,000 per person. However, this amount can change based on three critical factors: transferability, tapering, and the value of the residence.
1. Transferable Amount
If a spouse or civil partner dies without using their full RNRB (often because they left their share of the home to the surviving spouse), the unused percentage is transferred to the survivor. For example, if the first spouse used 0% of their RNRB, the survivor gets an extra 100% of the current rate added to their own allowance. This means a couple can potentially claim up to £350,000 in RNRB.
2. The Taper Threshold
The allowance is aimed at helping main residences pass down generations, not necessarily for very wealthy estates. If the net value of the estate (assets minus liabilities) exceeds £2 million, the RNRB is tapered (reduced). The reduction is £1 for every £2 that the estate exceeds the £2 million threshold.
3. The Residence Cap
Crucially, the RNRB cannot be greater than the value of the home itself. Even if your potential allowance is £350,000, if the home is only worth £300,000, your relief is capped at £300,000.
Who counts as a Direct Descendant?
To qualify for the RNRB, the property must be left to direct descendants. This definition is broader than just children and includes:
Children, grandchildren, and great-grandchildren.
Step-children and adopted children.
Foster children.
Spouses or civil partners of the above.
Leaving the property to siblings, nieces, nephews, or friends does not qualify for this specific relief.
function calculateTransferableRNRB() {
// 1. Constants for 2024/25 Tax Year
var STANDARD_RNRB = 175000;
var TAPER_THRESHOLD = 2000000;
var TAPER_RATE = 2; // £1 lost for every £2 over
// 2. Get Inputs
var estateValue = parseFloat(document.getElementById("estateValue").value);
var residenceValue = parseFloat(document.getElementById("residenceValue").value);
var unusedPercentage = parseFloat(document.getElementById("unusedPercentage").value);
var directDescendantSelect = document.getElementById("directDescendant").value;
var isDirectDescendant = (directDescendantSelect === "yes");
// Validate Inputs
if (isNaN(estateValue) || isNaN(residenceValue) || isNaN(unusedPercentage)) {
alert("Please enter valid numbers for all fields.");
return;
}
if (unusedPercentage 100) {
alert("Unused percentage must be between 0 and 100.");
return;
}
// 3. Calculate Transferable Amount
// The transfer is based on the % unused applied to the CURRENT rate.
var transferAmount = STANDARD_RNRB * (unusedPercentage / 100);
// 4. Calculate Total Potential RNRB (before tapering)
var totalPotentialRNRB = STANDARD_RNRB + transferAmount;
// 5. Calculate Tapering
var taperAmount = 0;
if (estateValue > TAPER_THRESHOLD) {
var excess = estateValue – TAPER_THRESHOLD;
taperAmount = excess / TAPER_RATE;
}
// Apply Taper
var postTaperRNRB = totalPotentialRNRB – taperAmount;
if (postTaperRNRB < 0) {
postTaperRNRB = 0;
}
// 6. Apply Residence Cap
// The RNRB cannot exceed the value of the residence
var finalRNRB = Math.min(postTaperRNRB, residenceValue);
// 7. Check Direct Descendants Rule
if (!isDirectDescendant) {
finalRNRB = 0;
}
// 8. Formatting Function
var formatter = new Intl.NumberFormat('en-GB', {
style: 'currency',
currency: 'GBP',
minimumFractionDigits: 2
});
// 9. Update UI
document.getElementById("transferredAmountDisplay").innerHTML = formatter.format(transferAmount) + " (" + unusedPercentage + "%)";
document.getElementById("potentialTotalDisplay").innerText = formatter.format(totalPotentialRNRB);
// Show/Hide Taper Row
var taperRow = document.getElementById("taperRow");
if (taperAmount > 0) {
taperRow.style.display = "flex";
document.getElementById("taperAmountDisplay").innerText = "-" + formatter.format(taperAmount);
} else {
taperRow.style.display = "none";
}
document.getElementById("residenceCapDisplay").innerText = formatter.format(residenceValue);
document.getElementById("finalResultDisplay").innerText = formatter.format(finalRNRB);
// Warning for non-descendants
var warningDiv = document.getElementById("descendantWarning");
if (!isDirectDescendant) {
warningDiv.style.display = "block";
} else {
warningDiv.style.display = "none";
}
// Show Results Section
document.getElementById("results").style.display = "block";
}