Declaration of trust

A declaration of trust is a legal document that records the beneficial ownership of a property, the shares in which each owner is entitled to the rental income and the sale proceeds, which can differ from the legal title registered at the Land Registry. Landlords use one most often to hold a property in unequal shares and split the rental income for tax. Where the owners are a married couple or civil partners, they must also file Form 17 with HMRC for that split to apply to income tax.

What a declaration of trust does

A declaration of trust, sometimes called a deed of trust, sets out the beneficial ownership of a property: who is entitled to the economic benefits, meaning the rental income while it is let and the proceeds when it is sold. The legal title at the Land Registry names the legal owners, but the declaration governs the financial split between them, and the two do not have to match. The shares can be equal or unequal, for example 60/40 or 90/10.

Landlords use a declaration of trust to reflect unequal deposit contributions, to define the shares of unmarried co-owners, to direct each owner's share to their chosen beneficiaries on death, and, most commonly, to split rental income for tax. For the income split to be possible, the property must be held as tenants in common rather than as joint tenants, because joint tenants own the whole equally and have no separate shares to divide. The difference between the two structures, and which suits a portfolio, is covered in our guide to tenants in common versus joint tenants.

Splitting rental income: the 50/50 rule and Form 17

For married couples and civil partners who live together, income from a jointly held property is taxed 50/50 by default under section 836 of the Income Tax Act 2007, regardless of the actual beneficial shares. To be taxed on unequal shares instead, a couple must do two things: hold the property as tenants in common in genuinely unequal beneficial shares, recorded in a declaration of trust, and file Form 17 with HMRC within 60 days of signing the declaration, with the declaration as evidence.

Two rules catch people out. The income split must match the capital split, so a couple cannot take the rental income 90/10 while keeping the eventual gain 50/50. And Form 17 does not itself change ownership: if the beneficial shares are actually equal, it has no effect, and it cannot be used at all where the property is held as joint tenants. The election is not backdated, it takes effect from the date of the declaration, and any later change to the shares voids it and requires a fresh deed and a new Form 17.

Unmarried owners and other co-owners

The 50/50 rule applies only to married couples and civil partners. Unmarried co-owners, business partners, siblings or friends are taxed automatically on their actual beneficial shares as set out in the declaration of trust, with no Form 17 required. If two unmarried owners hold a property 70/30 under a declaration of trust, the rental income is taxed 70/30, and each reports their share on their own Self Assessment return.

Tax interactions: capital gains and stamp duty

A declaration of trust has knock-on effects beyond income tax. A transfer of a beneficial share between spouses or civil partners who live together is treated as no gain, no loss for capital gains tax, so the transfer itself triggers no charge, though the receiving spouse takes on the original base cost. Stamp duty can arise where the person taking a larger share also takes on a corresponding share of the mortgage, because assumed debt counts as chargeable consideration and can exceed the threshold. Both points are worth checking before signing, as the saving on income tax can be offset by a charge elsewhere.

How a declaration of trust is made

A declaration of trust is normally drawn up by a solicitor, signed by all the owners and witnessed. If the property is currently held as joint tenants, the joint tenancy has to be severed first so the owners hold as tenants in common. For a married couple, the Form 17 then has to reach HMRC within 60 days of the declaration being signed, or the election fails and the 50/50 default continues. From working with self-managing landlords, the most common mistake we see is a couple assuming that an unequal deposit means unequal tax, when for spouses the income stays split 50/50 until both the declaration and the Form 17 are in place.

Once the split is set, the record-keeping matters as much as the deed. Landlords using August to track a jointly held property tell us the value is keeping the deed, the Form 17 and each owner's share of the income and expenses in one place, because HMRC recognises the split on the strength of the evidence, and a misplaced deed is enough to unpick it. August's expense tracking records each owner's share against the property so the figures match the declaration at return time.

Declaration of trust and the law

The 50/50 default for married couples and civil partners sits in section 836 of the Income Tax Act 2007, and the mechanism to override it is Form 17, the Declaration of beneficial interests in joint property and income, set out in HMRC's guidance and the Trusts, Settlements and Estates Manual. As of 2026 these are the rules in force. The position is fact-specific and the interaction with capital gains and stamp duty can be significant, so both legal and tax advice are sensible before a declaration is signed.

Frequently asked questions

Do you need a declaration of trust to split rental income?

To split it unequally, yes, in practice. The declaration of trust is the evidence that the beneficial shares are unequal. For a married couple it must be backed by a Form 17 filed with HMRC; unmarried owners are taxed on the shares in the declaration without a Form 17.

What is Form 17?

Form 17 is the HMRC declaration by which married couples and civil partners ask to be taxed on their actual beneficial shares of jointly held property rather than the default 50/50. It must reach HMRC within 60 days of signing, with a declaration of trust as evidence, and the income split must match the capital split.

Can you split rental income any way you like?

No. The split has to reflect the genuine beneficial ownership recorded in the declaration of trust. You cannot pick a ratio that does not match the real shares, and for spouses the income and capital splits must be the same.

Does a declaration of trust change who owns the property?

It changes the beneficial ownership, who is entitled to the income and proceeds, but not necessarily the legal title at the Land Registry. The legal owners can stay the same while the beneficial shares between them are set or altered by the deed.