When you own rental property jointly with another person, Section 24 joint ownership creates complex tax implications that many landlords overlook. The mortgage interest restrictions don't simply split 50/50 — your tax liability depends on ownership structure, income allocation, and strategic elections available to married couples.
Section 24 limits mortgage interest relief to a basic rate tax credit (20%), but for joint owners, this restriction applies to each person's share of the mortgage interest based on their beneficial ownership or chosen income split. Getting this wrong can cost thousands in unnecessary tax.
How Section 24 Applies to Joint Property Ownership
Section 24 mortgage interest restrictions affect each joint owner individually, based on their share of the rental income and corresponding mortgage interest. The key principle is that each person's Section 24 calculation is separate, even though the property generates a single rental profit.
For example, if you and your partner own a rental property 50/50, generating £20,000 annual rental income with £8,000 mortgage interest, each person would typically report £10,000 rental income and £4,000 mortgage interest on their personal tax return.
Under Section 24, neither owner can deduct their £4,000 mortgage interest as an expense. Instead, they each receive a basic rate tax credit of £800 (20% × £4,000). This matters significantly if either person pays higher rate tax on their total income.
Joint Landlords Section 24: Ownership vs Income Split
The way joint landlords section 24 restrictions apply depends on whether you're splitting income based on legal ownership or have made an election for a different split.
Legal Ownership Split
By default, rental income and expenses (including mortgage interest) are split according to legal ownership percentages. If the property deed shows 60/40 ownership, that's how the rental profit and Section 24 restrictions are allocated for tax purposes.
This means the person owning 60% reports 60% of the rental income, 60% of the allowable expenses, and 60% of the mortgage interest subject to Section 24 restrictions.
Beneficial Ownership Differences
Sometimes legal ownership doesn't reflect the true beneficial ownership. If you contributed different amounts to the purchase or mortgage payments, you might argue for a different split based on beneficial ownership.
However, HMRC scrutinises beneficial ownership claims carefully. You need clear evidence of different contributions and formal documentation to support any split that differs from legal ownership.
Couples Rental Income Tax Split: The Form 17 Election
Married couples and civil partners have a unique advantage for couples rental income tax split under Section 24. You can elect to split rental income 50/50 regardless of actual ownership percentages, using Form 17.
How the 50/50 Election Works
The Form 17 election allows married couples to split all income from jointly owned property equally, even if one spouse owns 90% and the other owns 10%. This includes rental income, mortgage interest, and all other expenses.
For Section 24 purposes, this means each spouse reports 50% of the mortgage interest and receives 50% of the basic rate tax credit, regardless of who actually pays the mortgage.
Strategic Benefits of the Election
The 50/50 election can be particularly valuable when spouses have different tax rates. Consider this example:
- Property: £30,000 rental income, £12,000 mortgage interest
- Spouse A: Higher rate taxpayer (40%)
- Spouse B: Basic rate taxpayer (20%)
- Legal ownership: 100% Spouse A
Without the election, Spouse A pays higher rate tax on the full £18,000 profit (after other expenses) and gets basic rate relief on £12,000 mortgage interest. With the election, each spouse reports £15,000 rental income and £6,000 mortgage interest, potentially saving significant tax.
Making the Form 17 Election
You must make the Form 17 election jointly, and it applies to all jointly owned property, not just selected properties. The election remains in force until you revoke it, which you can only do by giving HMRC notice.
The election must be made by the 31 January following the end of the first tax year you want it to apply to. For the 2025/26 tax year, the deadline is 31 January 2027.
Section 24 Planning Strategies for Joint Owners
Understanding how Section 24 affects joint ownership opens up several planning opportunities, particularly as separate property income tax rates are introduced from April 2027.
Income Shifting Between Spouses
For married couples, shifting rental income to the lower-earning spouse can reduce the overall Section 24 impact. This works best when one spouse has unused personal allowance or basic rate band capacity.
Remember that from April 2027, property income will be taxed at 22% (basic rate) and 42% (higher rate), making income shifting even more valuable for couples where one spouse pays higher rates.
Timing Property Purchases
When buying additional rental properties, consider the ownership structure carefully. If one spouse will benefit more from mortgage interest relief due to their tax position, adjusting ownership percentages at purchase can optimise the Section 24 impact.
Mortgage Restructuring
Some joint owners restructure mortgages so that the lower-earning spouse takes on more of the mortgage debt (and therefore mortgage interest). However, this requires genuine change in liability and careful documentation.
Business Partnership Considerations
If your joint property ownership constitutes a business partnership (uncommon but possible), different rules apply. Partnerships can elect how to split profits and losses, which might differ from ownership percentages.
However, most joint property ownership doesn't reach the threshold for partnership treatment. You'd typically need significant additional services beyond basic letting to be considered a partnership for tax purposes.
Record Keeping for Joint Owners
Joint property owners need meticulous records to support their chosen income and expense split. This includes:
- Property purchase documentation showing ownership percentages
- Evidence of contributions to purchase price and deposits
- Mortgage agreements showing liability split
- Bank statements showing who pays which expenses
- Copy of Form 17 election if applicable
With Making Tax Digital for Income Tax becoming mandatory from April 2026, digital record keeping will be essential for landlords with gross rental income over £10,000.
Common Mistakes with Joint Ownership and Section 24
Several errors commonly occur when joint owners deal with Section 24 restrictions:
Assuming Equal Split
Many joint owners assume rental income and expenses split 50/50, but this only applies if ownership is 50/50 or you've made a Form 17 election. Always check the actual ownership percentages.
Inconsistent Reporting
Each joint owner must report their share consistently across all expenses and income. You can't cherry-pick which items to split differently unless you have proper elections or agreements in place.
Ignoring Form 17 Opportunities
Married couples often miss the Form 17 election opportunity, which can provide significant tax savings when spouses have different tax rates.
Poor Documentation
Joint owners frequently lack proper documentation to support their chosen split, particularly when claiming beneficial ownership differs from legal ownership.
Looking Ahead: 2027 Property Tax Changes
From April 2027, property income will be subject to separate tax rates (22% basic, 42% higher, 47% additional), making income splitting strategies even more important for joint owners.
The Form 17 election will become more valuable as the gap between basic and higher rate property tax widens. Joint owners should review their elections and ownership structures before these changes take effect.
For detailed guidance on the current Section 24 rules, see our complete Section 24 guide. If you're considering incorporation to avoid Section 24 entirely, our limited company guide covers the key considerations.
Getting Professional Help
Section 24 calculations for joint owners can be complex, particularly when combined with other tax planning strategies. The stakes are higher with the 2027 property tax changes approaching.
A specialist property accountant can help optimise your ownership structure, ensure compliance with joint ownership rules, and plan for the upcoming tax changes. They can also advise on whether incorporation might be beneficial for your specific circumstances.