The related property rules for IHT

The related property rules in section 161 of the Inheritance Tax Act 1984 stop a couple reducing inheritance tax by splitting an asset between them. If an asset would be worth more as part of a combined holding with property owned by a spouse or civil partner (or recently given to a charity or similar body), it is valued as its share of that combined value. If the asset is sold within three years after death for less than that value, section 176 lets the executors claim to have it revalued on its own.

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What counts as related property?

Under section 161(2) and HMRC’s Inheritance Tax Manual at IHTM09733, property is related to property in a person’s estate if it is:

comprised in the estate of that person’s spouse or civil partner; or
property that is, or within the previous five years has been, owned by a charity or held on charitable trusts, or owned by a qualifying political party, a registered housing association or one of the national bodies in Schedule 3, and that became so through an exempt transfer made after 15 April 1976 by the person or their spouse or civil partner.

The spouse limb is the one most people meet. The charity limb exists so that someone cannot give a slice of a valuable holding to charity under the charity exemption and then have their own remaining slice valued as a small minority. HMRC notes that if the charity sells the property to another such body, the five years run from that sale.

The rules apply to both lifetime transfers and transfers on death (IHTM09731).

How is the value worked out?

The method has two steps (IHTM09732). First, the property in the estate and the related property are treated as one unit and valued in the normal way. Second, the estate’s “appropriate portion” of that combined value is calculated. The related property value is used only if it is higher than the value of the property on its own; section 161(1) never reduces a value.

The general rule

Section 161(3) apportions the combined value according to the separate values of each item, each valued as if the other did not exist (IHTM09735). HMRC’s example uses two adjoining plots owned by a husband and wife, worth £40,000 and £10,000 separately but £80,000 together because one has no access without the other. The husband’s plot is valued on his death at £40,000 ÷ £50,000 × £80,000 = £64,000.

The special rule for shares

Section 161(4) applies where the items are identical, mainly shares of the same class. The apportionment is by number of shares, not by value (IHTM09736). In HMRC’s example, one spouse owns 40 of the 100 shares in a company and the other owns 30. On its own the 40 share holding is worth £8,000, but the combined 70 share holding is worth £28,000. The deceased’s shares are valued at four sevenths of £28,000, which is £16,000, double the stand alone figure.

Shares count as the same class only if a recognised stock exchange would treat them that way (section 161(5)). Where three or more items are combined, the general rule is applied first between categories and then the special rule within each category (IHTM09738).

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When do the rules actually change the tax bill?

Gifts and legacies between spouses are normally exempt, so the uplift has no effect where the asset passes to the surviving spouse. The rules bite where the asset goes to someone else while the spouse keeps related property. Common cases are:

Family company shares. Each spouse holds a minority stake, and one leaves theirs to the children. The value is based on the couple’s combined holding, which may carry control. Section 269(2) also counts related property when deciding whether a person has control of a company.
Jointly owned homes. A share in a jointly owned property would normally be discounted for joint ownership. IHTM09739 says the related property rules remove that discount, so the deceased’s share is a proportion of the full vacant possession value. HMRC adds that the rules do not apply where the share passes to the surviving spouse by survivorship, because the spouse exemption applies.
Property let to a spouses’ partnership. Where premises owned by one or both spouses are let to a partnership of which they are the only partners, HMRC asks the Valuation Office for the entirety value with vacant possession if full business relief is not available.
Lifetime gifts. A gift of shares to a child by one spouse is valued using the combined holding, which affects the amount of any potentially exempt or chargeable transfer.

Business relief and agricultural relief may reduce the value after it has been found. See our page on inheritance tax business relief.

What relief is available if the asset is sold after death?

Section 176 allows a claim where property valued under section 161 is sold within three years after the death. It also covers property valued together with other property in the estate that has never since the death been vested in the people selling it, for example two items held in separate trust funds (IHTM09755). If the claim succeeds, the value immediately before death is recalculated as if the property had not been valued with the related property (section 176(2)).

The relief does not replace the death value with the sale price. The valuation date stays immediately before death, and only the property actually sold is revalued (IHTM09753). In HMRC’s example at IHTM09752, a freehold let to the deceased’s wife was valued at £37,500 under the related property rules, being £30,000 ÷ £40,000 × £50,000. After a qualifying sale its death value is revised to its stand alone value of £30,000.

What conditions must the sale meet?

IHTM09754 lists the conditions, drawn from section 176(3) to (5):

The relief must be claimed.
The sellers must be the personal representatives or the people in whom the property vested immediately after the death, such as trustees or a surviving joint tenant. HMRC says this is likely to exclude a sale by a beneficiary under a will or intestacy (IHTM09756), so timing the sale before assets are transferred to beneficiaries is important.
The sale must be at arm’s length for a price freely negotiated at the time.
It must not be made in conjunction with a sale of the related property, so a husband and widow selling together to one buyer will not qualify.
No seller can be the same as, or connected with, the buyer.
The sellers must not obtain a right to buy back the property or any interest in it.
The price, adjusted for any change in circumstances since death, must be less than the related property value (section 176(4)). HMRC treats a change in market conditions, the state of the property or the remaining term of a lease as a difference in circumstances (IHTM09760).

For shares in a close company there is an extra test in section 176(5). The relief is lost if, between the death and the sale, the value of the shares falls by more than 5% because of an alteration in the company’s share or loan capital or the rights attached to its shares. HMRC refers these claims to its Shares and Assets Valuation team (IHTM09761).

If the asset is a building or other real property, a sale may also qualify for the separate relief for property sold at a loss within four years of death. IHTM09762 explains that the two reliefs have different conditions and, where both are claimed, the loss on sale relief is applied first.

How might this look in practice?

Illustration only. Ann and Bill each own 25 of the 100 ordinary shares in a trading company. Ann dies and leaves her shares to her son. A 25% holding alone is valued at £100,000, but the combined 50% holding is valued at £300,000, so Ann’s shares are valued at £150,000 under the special rule. Eighteen months later her executors sell the 25 shares at arm’s length to an unconnected investor for £105,000 while Bill keeps his. The executors can claim under section 176 to substitute the stand alone value of £100,000 at the date of death. If any business relief is due, it is then applied to the revised value.

What mistakes should executors and advisers avoid?

Valuing each spouse’s shares or property share separately with a minority or joint ownership discount, without checking whether related property applies.
Passing the asset to a beneficiary before the sale, which can take the sale outside section 176.
Selling the deceased’s and the survivor’s holdings together, which fails the “not in conjunction” test.
Assuming the relief brings the value down to the sale price. It brings it down only to the stand alone value at death.
Forgetting the charity limb when the deceased gave part of a holding to charity in the five years before death.

Related property values must be reported on the IHT400; see completing the IHT400. For the charity side, see gifts of assets to charity, and if family members want to rearrange who inherits, see deeds of variation.

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Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.