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Joint Borrower, Sole Proprietor Mortgages: Who They’re For & When They Work

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If you’re struggling with affordability on your own, you might have come across something called a Joint Borrower, Sole Proprietor (JBSP) mortgage. It’s a mouthful, but the idea is simple: someone else can help you borrow more, without owning any share of the property.

In this guide, we’ll break down how JBSP mortgages work, who they’re best for, and when they can be a smart solution.

What Is a Joint Borrower, Sole Proprietor Mortgage?

A JBSP mortgage allows an extra person (usually a parent or close family member) to go on the mortgage but not on the property deeds.

This means:

  • They share responsibility for paying the mortgage.

  • They don’t own any part of the home.

  • They’re not caught by the extra 3% stamp duty surcharge that applies to second-home ownership.

It’s basically a way to boost affordability without adding someone as a legal owner.

Why Would Someone Use a JBSP Mortgage?

To Increase Borrowing Capacity

If your income doesn’t stretch far enough on its own, a second applicant’s income can help you borrow more. This is especially common for:

  • First-time buyers facing high house prices

  • Single applicants

  • People with lower or inconsistent income

To Get on the Ladder Earlier

Instead of waiting to increase income, build savings or pay off debts, a JBSP mortgage can speed up the process.

To Avoid Family Members Owning Part of the Home

Parents often want to help, but don’t want to be tied to the property legally. JBSP works perfectly here.

To Avoid Stamp Duty Surcharge

If a parent went on the deeds, they may pay the additional 3% stamp duty. JBSP avoids this because the helper isn’t a legal owner.


Who Are JBSP Mortgages Ideal For?

JBSP is most commonly used by:

 First-time buyers

Especially young professionals whose incomes haven’t caught up with house prices in their area.

Parents helping adult children

This is by far the biggest category. Parents can use their income to support the mortgage while the child owns the home.

Couples where one partner has lower income or credit issues

If one person can’t go on the mortgage (credit, affordability, past financial issues), they can still live in the property while the other partner and a helper apply.

Single parents

Where one income alone isn’t enough to meet lender affordability models.

 Older borrowers

Sometimes adult children go on the mortgage to help parents downsize or move, though lenders vary on age limits.


How a JBSP Mortgage Works (Step-by-Step)

  1. Borrower + helper(s) apply for the mortgage together.

  2. Lender assesses all incomes, commitments and credit files.

  3. Only the main buyer (the sole proprietor) goes on the property deeds.

  4. The mortgage offer names all applicants, who share the legal responsibility for the loan.

  5. Everyone must pass affordability, credit, age criteria and take independent legal advice.

  6. Over time, the helper can often be removed from the mortgage when affordability improves.


Pros of a JBSP Mortgage

  • Boosts affordability significantly

 

  • Can help you borrow more than you could alone.

 

  • No extra stamp duty for the helper

 

  • Parents, siblings or partners help without owning part of the home

 

  • Flexible exit — they can come off later

 

  • Good for long-term affordability growth

 

  • Perfect for careers with strong income progression.

Cons to Consider

  • All borrowers are legally responsible for the full mortgage

 If payments are missed, everyone’s credit file is affected.

  • Age limits can restrict mortgage terms

If the helper is older, their age may reduce the maximum mortgage term.

  • The helper’s borrowing may be affected

Their income is tied to this mortgage, which can limit their future applications.

  • Some lenders require legal advice

Independent legal advice is often mandatory for the non-owner borrower.


When Does a JBSP Mortgage Work Best?

When the main buyer’s income is rising

For example, early-career roles with strong salary progression.

When the helper has stable, strong income

Often a parent or relative with good credit and minimal debts.

When other options don’t fit

Such as when:

  • A guarantor mortgage isn’t available

  • A gifted deposit still isn’t enough

  • A partner can’t go on the mortgage

When avoiding stamp duty surcharge matters

A JBSP mortgage can work really well when one partner already owns a property and the couple want to buy a home together, but don’t want the existing property to trigger the additional 3% stamp duty surcharge.
Instead of adding the partner who already owns a property to the deeds, they can simply go on the mortgage to support affordability — avoiding the second-home tax charge.


When JBSP Might Not Be Suitable

  • If the helper wants to own part of the home → Joint mortgage may be better.

  • If the helper is near retirement → affordability may be restricted.

  • If the buyer’s income won’t realistically improve → removal later may be hard.

  • If multiple applicants already have commitments → affordability may still fall short.


Can the Helper Be Removed Later?

Yes — this is one of the best parts of JBSP mortgages.

Once the main borrower’s income improves, or once debts are reduced, you can request a remortgage or product transfer to remove the helper.


Is a JBSP Mortgage Right for You?

Every situation is different. A JBSP mortgage can be incredibly helpful for buyers who need extra support to get onto the property ladder, but it isn’t right for everyone.

Speaking with a broker gives you personalised guidance, checks lender criteria, and helps you choose the right solution for your circumstances.


Need Advice?

If you’d like to explore whether a JBSP mortgage could work for you, we’re happy to help.

Get in touch and we can run through your options, affordability and the lenders offering JBSP products right now.

As the New Year dawns, people will ask many questions about what the year ahead will bring them. For those whose chief aim is to buy a new home, the issue is whether now – or at least this year – will be a good time to get a mortgage.

Last year was clearly a difficult one for the property market, with prices falling (albeit less than many expected), inflation squeezing real incomes and making it hard to raise deposits, plus higher mortgage rates due partly to the lingering effects of the misfiring September 2022 ‘mini-Budget’ and a series of base rate rises by the Bank of England.

All that meant fewer mortgages and lower levels of house price purchases, but the landscape could be changing in a way that creates something of a sweet spot in the market for some buyers.

That ideal would be for mortgage costs to fall, with inflation easing (making it easier to save for a deposit), all while house prices do not return to an inflationary pattern.

Could 2024 be such a year? The stage has been set by a 2023 of modest house price falls. The final Nationwide House Price Index of the year indicated that across the last 12 months, the average cost of a home sold with a mortgage (as opposed to cash buyers) fell by 1.8 per cent.

Most house price surveys over the course of 2023 had indicated similar overall small drops, but often with significant regional variations, with the south and east seeing prices fall and places further north experiencing a slight increase. However, the Nationwide survey showed only Scotland and Northern Ireland had seen prices rise over the full year.

Nonetheless, falls in northern and Midland areas were more modest than in the south and east, with East Anglia seeing the greatest fall at 5.2 per cent, followed by the ‘outer south east’ at 4.5 per cent.

This means that people planning to see a mortgage advisor may see more comparative bargains in Oxford than in Oswestry, Ormskirk, Oban, or Omagh.

Just as importantly, the experts at Nationwide do not expect prices to start shooting up anytime soon. Nationwide’s chief economist Robert Gardiner predicted that prices will either be flat or at least only see modest increases.

He remarked: “Even though house prices are modestly lower and incomes have been rising strongly, at least in cash terms, this hasn’t been enough to offset the impact of higher mortgage rates.”

Given these are three times what they were even in the midst of the pandemic, he suggested the market will remain subdued. 

However, there may be good reasons to expect mortgage costs to fall somewhat this year. Firstly, there is increasing competition, with the opening days of 2024 seeing what some see as the opening salvoes in a mortgage rate price war. Halifax started by cutting its fixed rates by nearly one per cent, with Leeds Building Society following with its own cuts.

Furthermore, we may be seeing the Bank of England base rate start to fall sooner than some expect. After 14 successive increases, the Monetary Policy Committee has held the rate in its last three meetings.

While the minutes of the latest meeting revealed the expectation is the target Consumer Prices Index inflation rate of two per cent will not be reached until the back end of 2025, the inflation rate has been dropping more rapidly than broadly expected in recent months.

As recently as September it was 6.7 per cent, but then dropped to 4.6 per cent in October and 3.9 per cent in November. This may suggest a return to two per cent could arrive a lot sooner than late 2025, which could provide more wriggle room for rate cuts.

The latest wider economic news has been gloomy; the UK could be on the verge of recession after the October figures showed a decline in gross domestic product over the previous three months.

However, a consequence of this could be that rate cuts come sooner. A recession, even a very mild one, will do nothing to send house prices soaring, but will curb inflation further and could prompt a looser monetary policy that brings cheaper mortgages.

Of course, a weak economy is never good news for the housing market as a whole, since people fearing for their jobs will be less willing to commit to such a big financial step. But for those in sufficiently safe employment, 2024 could bring affordable prices and cheaper mortgages. It won’t be a good year for all, but for some house buyers, it could be great.