Joint Borrower Sole Proprietor Mortgages:
A Modern Alternative to Guarantor Mortgages

The UK mortgage landscape has evolved markedly in recent years. One of the most significant shifts has been the decline of the traditional guarantor mortgage in favour of the rising popularity of the Joint Borrower Sole Proprietor (JBSP) mortgage. Both models are aimed at enabling homeownership with family support, but JBSP products are increasingly favoured by lenders and advisers. As affordability pressures persist and lending criteria tighten, the JBSP structure offers a fresh route for many aspiring buyers.

Your home may be repossessed if you do not keep up repayments on a mortgage or any other debt secured on it.

Why the Shift from Guarantor to JBSP?

Under the older guarantor mortgage model, a family member (typically a parent) would act as guarantor: if the borrower missed repayments, the guarantor was legally liable to cover them. Over time, this model waned because lenders grew increasingly wary of the guarantor’s risk exposure; affordability rules tightened and regulatory scrutiny increased.

The JBSP model has emerged as a more transparent, lender-friendly alternative. Rather than simply guaranteeing the borrower’s payments, a parent or relative becomes a joint borrower. Their income is added to the affordability assessment. However, only the main applicant holds legal title (“sole proprietor”) to the home. This structure aligns more neatly with the Financial Conduct Authority’s mortgage rules (Mortgage Conduct of Business, or MCOB) around clarity of ownership, responsibility and affordability.

What Is a Joint Borrower Sole Proprietor (JBSP) Mortgage?

A JBSP mortgage allows two or more individuals—often 2–4—to be named on the mortgage application and loan contract, even though only one person owns the property and appears on the deeds. In effect:

• The supporting borrower(s) (e.g., a parent) contribute income for affordability calculations.
• The main borrower (e.g., the child) is sole proprietor on title and legally owns the property.
• All borrowers are liable for the mortgage repayments, but only the main borrower has ownership rights.

This model is especially useful for first-time buyers who may struggle to meet lender income thresholds alone. A parent adding income can enable the purchase without becoming a co-owner.

Key Benefits of JBSP Mortgages

JBSP mortgages bring several advantages over traditional guarantor models:

• Affordability boost: by combining incomes, the loan size can rise without transferring ownership.
• Ownership simplicity: ownership remains with the main borrower; the supporting borrower is not on the title.
• Reduced stamp duty implications: because the supporting party does not acquire ownership, certain stamp duty or additional property tax issues may be avoided.
• Flexibility: many lenders allow the supporting borrower to be removed (e.g., via remortgage) once affordability improves.
• Regulatory clarity and lender acceptance: the model sits well with current regulatory frameworks and lending policy.

Who Can Benefit from a JBSP Mortgage?

JBSP mortgages are particularly suitable for:

• First-time buyers whose income alone may not qualify for the required loan size but who can rely on a family member’s income.
• Young professionals with strong future earning potential but currently limited income.
• Families looking to support younger relatives into homeownership without taking legal ownership themselves.
• Individuals who wish to keep property ownership in their own name from the outset while still receiving financial backing.

At Mortgage One Finance, as a qualified mortgage adviser, we work closely with families to assess all parties’ incomes, expected liabilities and the long-term sustainability of the mortgage structure.

How JBSP Mortgages Work in Practice

When applying for a JBSP mortgage:

• The lender undertakes full affordability checks on all borrowers on the loan.
• The main borrower appears on the property title deeds; supporting borrowers do not.
• Because multiple incomes are assessed, the main borrower may access a higher loan amount than would be possible alone, but all parties remain liable for repayments.
• Later, once the supporting borrower’s removal is required (e.g., the main borrower can afford the mortgage independently or is remortgaging), a process is typically available to restructure or remove the supporting party.

What to Consider (and Possible Risks)

While the JBSP route offers many advantages, prospective applicants and their families should be aware of a number of important considerations:

• The supporting borrower’s credit file will reflect the mortgage debt until the supporting party is removed.
• The supporting borrower remains legally liable for the mortgage; if repayments fall into arrears, they may face consequences.
• Ownership remains with the main borrower—should the supporting party wish for security (e.g., through legal charge or trust), this must be separately arranged.
• Lenders have differing criteria: deposit size, maximum number of borrowers, maximum combined loan-to-income multiple, and supporting borrower age limits all vary.
• Just because a lender offers JBSP does not guarantee suitability: affordability, long-term sustainability and future flexibility must all be assessed.

The Future of Family-Assisted Borrowing

As affordability challenges persist for homebuyers—particularly first-time buyers—models such as JBSP are likely to remain a key feature of the UK mortgage market. The structure’s clarity, regulatory compatibility and growing lender familiarity make it a robust alternative to the older guarantor model, which has largely fallen out of favour.

For families helping younger relatives, it offers a way to provide meaningful support without complicating ownership structures or facing stamp duty or ownership-transfer issues.

Conclusion

The shift from guarantor mortgages to JBSP represents a broader evolution in the mortgage market: towards more transparent, flexible, lender-friendly and borrower-sustainable solutions. JBSP products give families the option to stand alongside younger buyers in a structured and compliant way—aligning ownership with the borrower while supporting affordability.

If you’re exploring family-assisted borrowing and wondering if a JBSP approach is right for you, speak to our team at Mortgage One Finance. We can explain your options and timings based on your unique circumstances. (Information only: not advice.)

FAQs

1. What is the difference between a JBSP mortgage and a guarantor mortgage?
A guarantor mortgage involves a third party guaranteeing payments; if the borrower defaults the guarantor is liable. In contrast, a JBSP mortgage makes the supporting party a joint borrower, their income is assessed, and they share liability—but only the main borrower owns the property.

2. Can parents help their children buy a house without being on the title deeds?
Yes. With a JBSP mortgage the parent can support affordability without becoming a property owner.

3. Will a JBSP mortgage affect the parent’s credit record?
Yes. As a joint borrower the parent’s credit file reflects the mortgage until their removal is arranged.

4. Can someone be removed from a JBSP mortgage later?
Yes. Once the main borrower can afford the loan without the supporting borrower’s income, many lenders allow the supporting party’s removal (often via remortgage).

5. Are JBSP mortgages available for buy-to-let properties?
Generally no. JBSP products are designed for owner-occupier residential purchases and not for most buy-to-let arrangements.

6. Are JBSP mortgages regulated by the FCA?
Yes. They fall under the FCA’s MCOB rules for responsible mortgage lending.

7. Do JBSP mortgages have age limits for supporting borrowers?
Yes. Lenders vary, but many apply age limits based on the oldest borrower so the supporting borrower’s age at the end of the loan term is a key factor.

8. What deposit is required for a JBSP mortgage?
Deposit requirements vary by lender and borrower profile—some start from around 5% deposit, but eligibility and affordability remain crucial.

9. Can more than two people be on a JBSP mortgage?
Yes. Some lenders permit up to four borrowers in a JBSP structure, though criteria vary.

10. Where can I get professional advice on JBSP mortgages?
You should speak to a qualified mortgage adviser. Mortgage One can help you understand your options.