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.

Buying your first home is an exciting milestone, but navigating the process of securing your first mortgage can feel overwhelming. From understanding the types of mortgages available to gathering the necessary documents, there are several crucial steps to take. In this comprehensive guide, we’ll walk you through everything you need to know to successfully secure your first mortgage in the UK.

Understanding Mortgages

Before diving into the process, it’s essential to understand the basics of mortgages. A mortgage is a loan specifically used to purchase property. In the UK, there are various types of mortgages, including fixed-rate mortgages, variable-rate mortgages, and tracker mortgages.

Fixed-Rate Mortgages: With a fixed-rate mortgage, your interest rate remains the same for a set period, typically two to five years. This provides stability in your monthly payments, making budgeting easier.
Variable-Rate Mortgages: The interest rate on a variable-rate mortgage can fluctuate, impacting your monthly payments. While your payments may decrease if interest rates fall, they could rise if rates increase.
Tracker Mortgages: Tracker mortgages are linked to the Bank of England’s base rate, meaning your interest rate moves in line with changes to this rate.

Assessing Your Financial Situation

Before applying for a mortgage, it’s crucial to assess your financial situation realistically. Lenders will consider factors such as your income, employment status, credit history, and existing debts when determining whether to approve your application. Use a mortgage calculator to estimate how much you can afford to borrow and what your monthly repayments might look like.

Saving for a Deposit

One of the most significant hurdles for first-time buyers is saving for a deposit. The size of your deposit will influence the mortgage deals available to you, with larger deposits often resulting in better interest rates. Aim to save at least 5-20% of the property’s value for your deposit, although some lenders may require more for favorable terms.

Checking Your Credit Score

Your credit score plays a crucial role in the mortgage application process. Lenders use it to assess your creditworthiness and determine the interest rate they offer you. Before applying for a mortgage, obtain a copy of your credit report and check it for any errors. Take steps to improve your credit score if necessary, such as paying off outstanding debts and ensuring bills are paid on time.

Getting Mortgage Advice

Navigating the mortgage market can be complex, especially for first-time buyers. Seeking advice from a mortgage advisor can help you understand your options and find the best deal for your circumstances. Independent advisors can offer unbiased recommendations from the entire market, while advisors tied to specific lenders may have access to exclusive deals.

Choosing the Right Mortgage

Once you’ve assessed your finances and sought advice, it’s time to choose the right mortgage for you. Consider factors such as the interest rate, term length, and any associated fees. While a lower interest rate may seem appealing, be mindful of other costs, such as arrangement fees and early repayment charges.

Gathering Documentation

When applying for a mortgage, you’ll need to provide various documents to support your application. These may include:

Proof of identity (passport or driving license)
Proof of address (utility bills or bank statements)
Proof of income (payslips or tax returns)
Details of existing debts and financial commitments

Gather these documents in advance to streamline the application process.

Applying for a Mortgage

With your finances in order and documentation prepared, it’s time to apply for your mortgage. You can apply directly to lenders or through a mortgage broker. Be prepared for the application process to involve affordability assessments and credit checks. Once your application is submitted, the lender will review it and make a decision.

Understanding Mortgage Fees

In addition to the interest rate, there are various fees associated with mortgages that you need to be aware of:

Arrangement Fees: Charged by the lender for setting up the mortgage.
Valuation Fees: Covers the cost of assessing the property’s value.
Legal Fees: Covers the cost of solicitors or conveyancers.
Early Repayment Charges: Penalties for paying off the mortgage early.

Read the terms and conditions carefully to understand all the fees associated with your mortgage.

Completing the Purchase

Once your mortgage application is approved, you’re one step closer to owning your first home. The final steps involve exchanging contracts with the seller and completing the purchase. Your solicitor or conveyancer will handle the legal aspects of the transaction, ensuring everything is in order before the keys are handed over.

Conclusion

Securing your first mortgage in the UK is a significant milestone on the journey to homeownership. By understanding the types of mortgages available, assessing your financial situation, and seeking advice where necessary, you can navigate the process with confidence. Remember to carefully compare mortgage deals, gather the necessary documentation, and budget for associated fees. With careful planning and preparation, you’ll soon be opening the door to your new home.