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.

In the dynamic realm of the UK’s mortgage market, April 2024 emerges as a pivotal juncture, marked by a confluence of factors shaping the borrowing landscape. From policy shifts to market trends, this article delves into the latest developments, offering insights into what lies ahead for aspiring homeowners, existing borrowers, and industry stakeholders.

Policy Pivot: The Impact of Regulatory Changes

At the forefront of April’s mortgage news is the ripple effect of regulatory changes, influencing lending practices and borrower eligibility criteria. The implementation of the Financial Conduct Authority’s (FCA) Mortgage Market Review (MMR) guidelines continues to exert its influence, ensuring responsible lending practices and enhancing consumer protection.

One notable development is the ongoing scrutiny of affordability assessments, with lenders mandated to conduct thorough evaluations to ascertain borrowers’ financial capabilities. This heightened scrutiny aims to prevent over-leveraging and mitigate the risk of defaults, fostering a more sustainable lending environment.

Moreover, the regulatory landscape witnesses the interplay of macroeconomic dynamics, with the Bank of England’s monetary policy stance influencing interest rates. As inflationary pressures persist, fueled by global supply chain disruptions and rising energy prices, the prospect of interest rate adjustments looms large. Such fluctuations can significantly impact mortgage affordability, warranting vigilance among borrowers and lenders alike.

Housing Market Trends: Navigating Supply and Demand Dynamics

Against the backdrop of regulatory reforms, the UK’s mortgage market grapples with evolving supply and demand dynamics, underscoring the need for adaptability and strategic foresight. Amidst a backdrop of robust demand fueled by demographic shifts and housing aspirations, supply-side constraints persist, exerting upward pressure on property prices.

The emergence of innovative mortgage products tailored to diverse borrower profiles reflects a paradigm shift in the lending landscape. From green mortgages incentivizing sustainable homeownership to shared ownership schemes facilitating access for first-time buyers, lenders are increasingly diversifying their offerings to cater to evolving needs and preferences.

Furthermore, technological advancements catalyze digital transformation within the mortgage ecosystem, streamlining processes and enhancing accessibility. From digital mortgage applications to automated underwriting systems, technology fosters efficiency and transparency, empowering borrowers to navigate the mortgage journey with greater ease and convenience.

Housing Affordability Challenges: Navigating the Housing Affordability Conundrum

Despite the array of mortgage options available, affordability remains a pressing concern for many aspiring homeowners, particularly amid escalating property prices and stagnant wage growth. The disparity between housing costs and household incomes underscores the need for targeted interventions to foster inclusive homeownership.

Government initiatives such as the Help to Buy scheme and the Affordable Housing Programme seek to bridge the affordability gap, offering financial assistance and promoting the construction of affordable housing units. However, persistent structural challenges, including land availability constraints and planning regulations, pose formidable obstacles to achieving widespread affordability.

Addressing the affordability conundrum necessitates a multifaceted approach, encompassing policy interventions, private sector initiatives, and community-led solutions. Collaborative efforts aimed at enhancing housing supply, promoting sustainable development, and empowering marginalized communities are integral to fostering a more inclusive housing market.

Regional Disparities: Exploring Regional Variations in Mortgage Dynamics

The UK’s mortgage market exhibits notable regional disparities, with distinct patterns of lending activity and affordability dynamics across different geographic areas. While London and the Southeast remain perennially sought-after property hotspots, characterized by buoyant demand and premium prices, other regions witness more subdued market conditions.

Regional variations in economic performance, demographic trends, and infrastructure investment underpin disparities in housing market dynamics, influencing mortgage lending patterns and borrower preferences. From the affordability challenges plaguing urban centers to the burgeoning demand for rural properties driven by lifestyle shifts, regional nuances shape the evolving mortgage landscape.

Navigating these regional disparities requires tailored strategies and localized solutions, encompassing targeted interventions to address affordability constraints, stimulate housing supply, and promote inclusive growth across diverse communities.

Looking Ahead: Navigating Uncertainties and Seizing Opportunities

As April 2024 unfolds, the UK’s mortgage market stands at a crossroads, characterized by a blend of regulatory reforms, market trends, and affordability challenges. Amidst the uncertainties and complexities, opportunities abound for stakeholders to adapt, innovate, and collaborate in shaping a more resilient and inclusive housing ecosystem.

From policymakers charting the course of regulatory reforms to lenders tailoring their offerings to meet evolving borrower needs, collective action is essential to foster a mortgage market that is equitable, sustainable, and responsive to the diverse needs of society. By embracing innovation, harnessing technology, and fostering collaboration, the mortgage industry can navigate the challenges ahead and unlock new pathways to homeownership for generations to come.