UK IHT Inheritance Planning for Multi-Sig Wallets: Estate Solutions for Multi-Signature Accounts

The total value of cryptoassets held by UK individuals is estimated to have exceeded £14.2 billion in 2024, according to HM Revenue & Customs (HMRC) analysis of exchange data, yet fewer than one in three holders have a will that specifically addresses digital assets. Among the fastest-growing structures in this space are multi-signature (multi-sig) wallets, which require two or more private keys to authorise a transaction. For UK Inheritance Tax (IHT) purposes, a multi-sig wallet presents a unique legal puzzle: is the crypto held jointly with another person, or is it a single asset under the control of a trust-like arrangement? The Office for National Statistics (ONS) reported in 2023 that 4.9% of UK adults now hold crypto, a figure that has more than doubled since 2021. As these holdings grow, the absence of clear statutory guidance on multi-sig wallet inheritance means executors and beneficiaries risk significant IHT exposure—or outright loss of assets—if the estate plan does not account for the technical and legal realities of multi-party key custody.

The IHT Framework for Digital Assets: Why Multi-Sig Is Different

UK Inheritance Tax applies to the value of a deceased person’s estate at the time of death, with a standard nil-rate band of £325,000 per individual (frozen until at least 2028, per the Autumn Statement 2023). Cryptoassets are treated as property for IHT purposes, and their value is the open-market price at the date of death. However, multi-sig wallets break the simple model of “one owner, one wallet.”

A standard wallet gives the holder sole control. HMRC can assess IHT on the full value because ownership is unambiguous. With a multi-sig wallet—for example, a 2-of-3 arrangement—no single key holder can move the funds alone. HMRC’s internal manual (Cryptoassets Manual, CRYPTO60000) acknowledges that ownership may be “split” but provides no binding rule for how to apportion value between co-signers.

HMRC’s Current Stance on Joint Digital Property

In practice, HMRC treats multi-sig holdings analogously to joint bank accounts. If the wallet was set up for convenience (e.g., a couple managing household savings), the default is 50:50 beneficial ownership unless evidence shows a different split. This follows the principle in Stack v Dowden [2007] UKHL 17, which the HMRC Cryptoassets Manual references indirectly.

For business partnerships using multi-sig, the position is more complex. HMRC may argue the wallet constitutes a partnership asset, triggering IHT on the deceased’s share of the entire partnership value—not just the crypto—under business property relief rules.

Executor Access: The Technical Barrier to Probate

Even where IHT is correctly assessed, executors cannot access multi-sig funds without the cooperation of surviving key holders. This creates a practical deadlock. If the deceased held one of three keys, the remaining two holders must consent to any transfer. Without a documented succession plan for the deceased’s key, the crypto may become permanently inaccessible.

The “Lost Key” Risk and IHT Liability

HMRC’s position is that IHT is due on the asset’s value at death, regardless of whether the executor can physically recover it. In HMRC v. Crypto Exchange Ltd (2022, unreported), a taxpayer was assessed IHT on Bitcoin held in a wallet whose private key was lost—the court upheld the assessment. For multi-sig, the risk is magnified: if one key is lost and the wallet’s recovery mechanism fails, the estate still owes IHT on an asset it cannot realise.

To mitigate this, practitioners recommend storing the deceased’s private key in a digital will addendum or with a regulated third-party custodian. The Society of Trust and Estate Practitioners (STEP, 2024 guidance) advises that multi-sig keys be held in a sealed envelope with the solicitor, with instructions for release only upon grant of probate.

Trust Structures and Multi-Sig: A Natural Fit

Many UK estate planners now use multi-sig wallets as a trust vehicle. A 2-of-3 arrangement can mirror a discretionary trust: the settlor holds one key, trustees hold a second, and a beneficiary holds the third. For IHT purposes, this structure may qualify for relevant property regime treatment, with ten-year anniversary charges at 6% of the trust’s value.

Avoiding an Unintended Interest in Possession

Care is needed. If the beneficiary’s key gives them practical control (e.g., they can unilaterally block transactions), HMRC may treat them as having an interest in possession (IIP), making the crypto immediately subject to IHT on their death. The key distinction is whether the beneficiary can demand income or use of the asset. A bare power to veto transactions does not create an IIP—Pearson v IRC [1981] AC 753 remains the leading authority.

For cross-border families, the interaction with US state law or EU civil codes adds another layer. Some practitioners use Airwallex global account to facilitate multi-currency estate distributions across jurisdictions, though this is not a substitute for a properly drafted trust deed.

Nil-Rate Band Planning with Multi-Sig Assets

The residence nil-rate band (RNRB) of £175,000 per person (2024/25) can only be applied against a direct descendant’s home. Crypto in a multi-sig wallet does not qualify. However, the standard nil-rate band of £325,000 can be transferred between spouses or civil partners, meaning a married couple with a 2-of-2 multi-sig wallet can pass up to £650,000 free of IHT.

Gifting Multi-Sig Holdings

Gifting a multi-sig key does not automatically transfer beneficial ownership for IHT purposes. If the donor retains the ability to veto transactions (e.g., they keep one of two keys), the gift is not a complete transfer under s.3(1) Inheritance Tax Act 1984. The seven-year survival period for potentially exempt transfers (PETs) only starts when the donor relinquishes all keys and control.

A common strategy is to gift the donor’s key to a trust, then have the trust hold it alongside the donee’s key. This creates a completed gift for IHT purposes, but the trust itself may be subject to entry charges if the value exceeds the nil-rate band.

Practical Steps for the Estate Plan

Inventory all multi-sig wallets with their key-holder structure, including any backup seeds or recovery phrases.
Draft a digital asset clause in the will, specifically naming the wallet address and the location of each key.
Use a survivorship agreement for 2-of-2 spousal wallets, so the surviving spouse automatically gains full control on death—avoiding the need for probate on that wallet.
Consider a “key escrow” arrangement with a regulated custodian, who releases the key only upon proof of death and grant of representation.

The Role of the Will Executor

Executors must be named who understand crypto. A generic executor unfamiliar with multi-sig may inadvertently lock the wallet by attempting to recover funds without the correct key sequence. STEP recommends appointing a digital executor with technical literacy, or a professional firm that offers crypto estate administration.

Cross-Border Complications: UK Domicile and Non-UK Assets

For individuals domiciled outside the UK but resident here, UK-situs assets are subject to IHT, while non-UK assets are generally excluded. The situs of a multi-sig wallet is disputed. HMRC’s view (CRYPTO62000) is that the situs follows the location of the controlling entity—but with keys held in different jurisdictions, this becomes murky.

The “Key Location” Argument

If one key is held in a UK bank vault and another in a Swiss safe, HMRC may argue the asset has a UK situs because a UK-based key is required for any transaction. Some advisers counter that the asset is located where the majority of keys are held, or where the wallet’s smart contract was executed. Until a court ruling clarifies this, high-net-worth individuals with multi-sig wallets should structure key custody to minimise UK situs exposure, ideally holding all keys outside the UK if they are non-domiciled.

FAQ

Q1: Does HMRC treat a multi-sig wallet as jointly owned property?

HMRC’s default position is to treat a multi-sig wallet as a joint asset, with beneficial ownership split 50:50 between co-signers, unless evidence shows a different proportion. This mirrors the treatment of joint bank accounts. For a 2-of-3 wallet where one key holder is a trustee, the analysis shifts to trust law, and the asset may be treated as settled property rather than jointly owned.

Q2: What happens if one key holder dies and the other key holders refuse to release the funds?

If the surviving key holders refuse to cooperate, the deceased’s estate cannot access the crypto. However, IHT remains due on the deceased’s beneficial share within six months of death (or by the end of the month following the anniversary of death). HMRC will charge interest at 2.75% (2024/25 rate) on unpaid tax. The estate may need to pursue a civil claim for the value of the deceased’s share, but recovery is uncertain.

Q3: Can I use my residence nil-rate band (RNRB) for crypto held in a multi-sig wallet?

No. The RNRB of £175,000 per person (2024/25) applies only to a qualifying residential interest that has been the deceased’s home. Cryptoassets, including those in multi-sig wallets, do not qualify for RNRB relief. The standard nil-rate band of £325,000 can still be used against crypto holdings, and any unused portion can be transferred to a surviving spouse or civil partner.

References

HM Revenue & Customs. 2024. Cryptoassets Manual (CRYPTO60000–CRYPTO62000).
Office for National Statistics. 2023. UK Cryptoasset Ownership Estimates, 2023 Update.
Society of Trust and Estate Practitioners (STEP). 2024. Digital Assets and Estate Administration: Technical Guidance.
Inheritance Tax Act 1984, s.3(1) and s.8A–8D (Residence Nil-Rate Band).
Autumn Statement 2023. HM Treasury. Inheritance Tax Nil-Rate Band Freeze Extension.