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

November 19th 2025

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)

Borrower + helper(s) apply for the mortgage together.
Lender assesses all incomes, commitments and credit files.
Only the main buyer (the sole proprietor) goes on the property deeds.
The mortgage offer names all applicants, who share the legal responsibility for the loan.
Everyone must pass affordability, credit, age criteria and take independent legal advice.
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.

Whilst this is not always the case, as people get older, they want to slow down and take advantage of the care, work and savings they have invested into over the course of decades, to ensure a better quality of life and more peace of mind whilst they can enjoy it most.

Without the pressure of a long-term mortgage, but before they have the complete peace of mind of a mortgage, many people in their 50s and older often have a lot of money that is locked away, inaccessible until they are older, access care services or sell their home outright.

However, there is a way to access money without waiting or taking out another form of conventional finance with the expensive repayment schedules they require, which takes the form of a lifetime mortgage and is accessible through a specialist broker.

It is not always an accessible option, but for homeowners over the age of 55, it can sometimes be the perfect way to get access to a considerable wealth store without having to sell a house.

To understand whether it is the right choice for you, it is important to know what it is, what it can do and what it isn’t.

What Is A Lifetime Mortgage?

A lifetime mortgage is a form of equity release, which allows you to take out some of the value in the home and receive it either in instalments (as a drawdown) or in a lump sum.

Specifically, a lifetime mortgage, contrary to its name, is not a conventional mortgage loan product. Instead, it is an equity release that allows a homeowner to borrow money against some of the home’s value which has accrued over time above and beyond the original mortgage price.

The advantage is access to a considerable amount of money that does not need to be paid back fully until after the homeowner dies or moves into long-term care permanently and thus does not have a house. They do have the option to pay back interest, which would accrue throughout the life of the mortgage and the person.

Exactly how much depends on the home and the age of the person, generally meaning that the older someone is, the more they could potentially borrow.

You can use the money however you like, repay it however you like and even move house, although most lifetime mortgage brokers do have particular expectations on maintaining the quality of the home or the quality of the new home, for example, if a homeowner wants to downsize.

There are some caveats of course. The house will be sold off at the end so it will reduce the amount left behind as an inheritance. Interest rates are higher in general, and it is essential to get a guarantee that there will be no negative equity.

Without this guarantee, if the value of the property goes down lower than the value of the lifetime mortgage on it, the difference will need to be paid for by the people who would have inherited it.

There are other options available, such as ringfencing some of a home’s value as part of the inheritance and to make sure they get something.

When Should You Take One?

There are a lot of reasons to take out a lifetime mortgage, and because of that, it tends to either be completely unsuitable or the perfect option.

One common use of a lifetime mortgage is to unlock money for adaptations and home improvements. Many people want to stay in their homes for as long as they can rather than enter residential care, and releasing the money can help them to keep living comfortably and safely in their homes for years into the future.

This can be beneficial if you pay off the loan early and its value skyrockets thanks to these improvements, although short-term finance options are typically preferable.

Another common use is to provide money to a family member now, rather than either having to sell the home or wait for the inheritance to be divided after death. Inheritance tax may still need to be paid on this gift so it is essential to keep that in mind.

Other times, it is about simply enjoying the money now rather than it sitting, inaccessible, and unable to be unlocked until after the homeowner has passed on. If they do not have family members to leave anything behind to, it is better to take advantage now.

Typically this means holidays or maybe some larger purchases such as cars, but lenders tend to be relaxed as long as they know the intentions for the money and it is not being used for overly risky endeavours such as buying a home abroad, gambling or investing in financial markets.