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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.

Many people dream of the day they can buy a property, rent it out, and then sit back and watch the cash roll in right? It sounds lovely, but in reality there is a lot more to buy to let properties, and as mortgage brokers we want you to be armed with the correct knowledge before making any decisions.

With the 3% stamp duty surcharges, a seemingly endless range of new legislation and regulations and high tax rates to contend with, it’s important to fully understand what to expect when either applying for a BTL property, or continuing with your current BTL mortgage deal.

To begin with, Bank of England figures estimated that by the end of the year monthly repayments for buy-to-let landlords could rise by £175, and a fifth of landlords monthly repayments could increase by over £300. Naturally, this increase means owning a buy to let property may no longer be financially viable for many landlords as the rent received isn’t sufficient to pass the higher stress test, meaning landlords are faced with either sitting on high SVR, selling or reducing the mortgage (which not everyone is able to do).

The tax advantage of renting also no longer exists in the same way it did before resulting in Buy-to-let mortgages no longer being tax-deductible, so many landlords face significant losses in the next few years.

As a result of this, Buy-to-let has become increasingly unprofitable for landlords with mortgages and many have decided to exit the sector, while those who currently remain are pondering the best way to adapt to the new market conditions.

On top of all this, the regulatory environment is getting tougher too. The Renters’ Reform Bill, which features a package of reforms to protect renters, is expected to be debated and voted on in Parliament very soon. And by 2026 all newly rented properties should be required to have an Energy Performance Certificate (EPC) rating of C or above, if this is achievable, you will need to spend £10,000 on an exemption. A few positives to this is the possible off set against tax, as well as the fact that tenants will have lower energy bills and therefore more money to pay rent, resulting in less defaults.

As we always say here at Bright Money Independent, “it’s not all doom and gloom” and there are some positives to BTL in 2023. If you’re a cash-rich landlord you may well be at an advantage as rental yields are increasing as rents rise so there will undoubtedly be some good properties to buy from “distressed sales.”

Also, due to higher interest rates, steeper affordability calculations and fewer 95% loan-to-value mortgages, many first-time buyers will delay buying a property this year and continue to save. But of course they still need somewhere to live. Therefore, rental demand is set grow throughout 2023, with rent continuing to rise at an extraordinary rate and, while they’re likely to slow this year, they won’t decrease.

Still unsure on what to do? (We get it, it’s overwhelming) but one solution could be to consider incorporating your BTL (buying the property under a ltd company name). If you’re in the higher tax bracket, you could be paying 40% tax on your income if your property is set up in your personal name, whereas if you set up a limited company, you’ll pay the lower corporation tax – which currently sits at 19%. However, this is likely to rise to 25% this year, which will affect your profits again.

And finally, some lenders are reducing stress tests now that rates are coming down will have products with lower interest rates & higher arrangement fees.

Although some of the recent changes make buy-to-let less attractive to some investors, if done right, it still remains profitable. Whilst rental yields have declined, it’s important to remember that although rental income is important, capital growth is also a factor that makes investing in property very lucrative.