If you own a rental property jointly with your spouse or civil partner, you might assume that the taxman simply looks at who paid for what or who collects the rent.

In reality, HMRC (or, for the geeks, section 836 of the Income Tax Act) defaults to a blanket 50:50 split for Income Tax, regardless of the actual split of ownership. If one of you is a higher rate taxpayer earning £60,000 and the other works part-time or stays at home, paying tax on half that rental income at the Higher Rate of tax can sting, knowing your partner would pay tax at the Basic Rate – or even lower – if the bulk of the rental profits could go on their tax return and be taxed at lower rates.

That is where Form 17 comes into play. It is an official declaration sent to HMRC to tell them that you own a property in unequal shares and wish to be taxed according to those actual shares rather than the default half-and-half split.

How the Default 50:50 Rule Works

When married couples or civil partners live together and hold property in joint names, tax law treats the rental income as if it belongs to both of you equally. It does not matter if one partner put up the entire deposit, pays the mortgage every month, or receives all the rent into their bank account. Unless you tell HMRC otherwise, you will each be taxed on 50% of the profit.

This equal split is fine if you both fall into the basic rate tax bracket. However, if one partner pays Income Tax at 40% or 45% while the other has unused Personal Allowance, splitting the income down the middle means you are paying significantly more tax as a household than you need to.

On the flip side, if one of you receives all the rental, it must be awful for the spouse who receives no income to still be expected to pay tax on half the profits!

The Magic of Form 17 and a Deed of Trust

Form 17 allows you to align your tax liabilities with your actual legal entitlement to the property. For example, if you own 90% of the property and your spouse owns 10%, Form 17 ensures that 90% of the rental profit is taxed on the partner with the lower income, with just 10% taxed on the higher earner.

However, there is a catch. You cannot simply pick any random split that suits your tax bill for the year. The income split must reflect the true underlying beneficial ownership.

To prove this to HMRC, you need to hold the property as tenants in common rather than joint tenants, and you must back up your Form 17 submission with evidence. This evidence usually takes the form of a legal document known as a Deed of Trust or Declaration of Trust, prepared by a solicitor (not an accountant, sorry – but we can put you in touch with a couple of great solicitors in and around Taunton who can sort this for you).

This document formally sets out that one partner owns a specific percentage of the capital and equity in the property.

First, some things you need to know

Before jumping in, there are a few strict ground rules you need to follow:

First, timing is everything. Once both of you have signed the Form 17 declaration, it must reach HMRC within 60 days, alongside your Deed of Trust. If you miss this deadline by even a day, HMRC will reject the form, and you will have to start the paperwork all over again.

Second, Form 17 cannot be backdated. The new income split only applies from the date the accepted Form 17 declaration is signed. This one is the real fly in the ointment – especially when a new client comes to us after the end of the tax year, not realising they needed to mess about with Form 17. They assume – understandably – that it can be backdated to when they first bought the property.

Thirdly, assuming the property is mortgaged, you may need the approval of your lender to change the underlying ownership of the property. So speak to them first before you start shelling out for solicitors, in case it’s a non-starter. In which case, look to have ownership adjusted when your current mortgage comes to the end of its current term.

And finally, if you transfer a share of property to your spouse, you also need to keep an eye on Stamp Duty Land Tax (SDLT). While transfers between married couples are usually exempt from Capital Gains Tax, taking on a share of an existing mortgage can sometimes trigger an SDLT liability. So let’s discuss that before you take action.

The Perfect Wedding Present?

Something that catches people out a lot is where an unmarried couple have owned a property jointly, and then they become married. With no further action, any unequal split of ownership from before the marriage is now rendered null and void, with 50/50 kicking in from the moment you sign the register.

Of course, if you’re planning to go into married life splitting everything 50:50, that’s great, no further action required. But if you want to keep the split efficient for tax planning, is there anything more romantic than taking a pre-filled Form 17 with you to the church?

How We Can Help

Getting the split right can save your household thousands of pounds in Income Tax every year, but doing it incorrectly risks penalties or a rejected claim from HMRC.

Navigating property taxes in general can feel like walking through a minefield. But Form 17 is something that fits into Colin Powell’s famous “Unknown Unknowns” – so few people even know it’s an issue, until it’s too late. By reading this blog, at least it’s now a “Known Unknown” for you.

So get in touch and make it a firm “Known Known” and let’s make sure the split of income between you and your spouse is as beneficial – and legal – as it can be.