Jointly Owned Rental Property — How Income Is Split for Tax Purposes in 2026

The Default Position: 50/50

When two or more people jointly own a rental property, HMRC's default assumption is that income and expenses are split **equally** between the owners — regardless of how much each person contributed to the purchase price, the mortgage, or ongoing costs.

For **married couples and civil partners** living together, this 50/50 split is not merely a default — it is a statutory rule under the Income Tax Act 2007. HMRC will tax each partner on half the rental income unless the couple takes formal steps to declare a different beneficial interest.

For **unmarried co-owners** (whether friends, siblings, or cohabiting partners), the default is also a 50/50 split, but the actual legal position follows the beneficial ownership of the property. If the property is held as tenants in common with unequal shares, each owner is taxed on their actual share of the income.

Why the Split Matters

If one owner pays Income Tax at the basic rate (20%) and the other at the higher rate (40%), splitting income unequally in favour of the lower-rate taxpayer can reduce the household's overall tax bill significantly. This is a legitimate form of tax planning when it accurately reflects the true beneficial ownership.

Form 17 — Changing the Split for Married Couples

Married couples and civil partners who genuinely hold unequal beneficial interests in a jointly owned property can elect to be taxed on their actual shares by submitting **Form 17** to HMRC. This must be done within **60 days** of the change in beneficial interest taking effect and must be accompanied by a **Declaration of Trust** (a formal legal document) confirming the unequal ownership.

Important caveats:

• Form 17 cannot be used to impose an artificial split that does not reflect genuine beneficial ownership. The actual shares must change first.
• Once submitted, the election remains in force until the underlying beneficial interests change again.
• Form 17 is not available to unmarried co-owners — their split simply follows actual beneficial ownership.

Declaration of Trust

To change beneficial interests, you typically need a solicitor to draft a **Declaration of Trust** (also called a Deed of Trust). This is a legal document confirming each party's percentage interest in the property and, often, their entitlement to income. It does not change the legal title held at HM Land Registry — it operates in the background as an equitable interest.

The combination of a Declaration of Trust plus Form 17 is the standard mechanism married couple landlords use to optimise the income split.

Tenants in Common vs Joint Tenants

• **Joint tenants** — each owner holds an undivided share of the whole. On death, the surviving owner automatically inherits the deceased's share. For tax purposes, joint tenants in a marriage are treated as 50/50 owners unless Form 17 is filed.
• **Tenants in common** — each owner holds a specified, separable share (e.g., 70% / 30%). On death, the share passes under the will or intestacy rules. For unmarried co-owners this is often the preferred structure if unequal contributions are made.

How the Tax Calculation Works in Practice

Once the split is established, each owner declares their share of the rental profit on their own Self Assessment return. Each can offset their own allowable expenses and mortgage interest credit proportionally. The Section 24 credit (20% of finance costs) is apportioned according to the same beneficial interest split.

Use our [rental income tax calculator](/rental-income-tax-calculator) to model different income splits and understand which arrangement best suits your household's tax position.