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Last updated: June 2025
A Joint Borrower Sole Proprietor mortgage lets a parent, family member or close friend boost someone's borrowing power — without being named on the property. It's one of the most flexible ways to get a first-time buyer into a home of their own.
A JBSP mortgage is a product where multiple people are responsible for the mortgage repayments, but only one person (or couple) is named on the property's title deeds as the legal owner.
This is the key difference from a standard joint mortgage — on a JBSP, the “helper” is legally on the hook for the mortgage but has no ownership stake in the property. This makes it particularly attractive for parents helping adult children buy their first home.
This setup lets another person, often a parent, guardian, or close family member join the mortgage to boost affordability. By combining incomes, the main buyer can borrow more and overcome the affordability barriers that often hold first-time buyers back from getting onto the property ladder.
The mechanics are straightforward, but they're important to understand fully before proceeding:
The most common use case. A parent's income supplements their child's to reach the required borrowing level — without creating a shared ownership.
First-time buyers who earn a good salary but not quite enough to borrow what they need solo. Adding a supporter's income bridges the gap.
Parents or family who already own their home can help without triggering SDLT surcharges or losing their first-time buyer status.
Single applicants who would struggle to qualify alone. A JBSP lets them access homeownership now while building their own income over time.
Only the buyer appears on the title deeds. The helper's income counts towards affordability but they have no ownership stake. No SDLT surcharge for the helper. Lender options are fewer not every lender offers JBSP products.
With the JPSB only the son or daughter’s name will be on the property’s deeds. This is because the parent’s name is listed on the deed of the home, but the child is not on the deeds of the property. It is true joint mortgages allow parents, children and partners to club together to get a mortgage. For a joint mortgage, you have no legal claim to the property, and only the child has a right to the deeds.
All borrowers appear on the title deeds as co-owners. Wider lender choice and often better rates, but the helper is treated as owning a second property — triggering a 3% SDLT surcharge and potentially affecting their own mortgage in future.
JBSP mortgages are a powerful tool, but both parties should go in with open eyes:
If the buyer misses payments, the helper is equally liable. This will affect both parties' credit files and could impact the helper's own mortgage or financial commitments.
The JBSP mortgage commitment will show on the helper's credit file. If they need to remortgage or apply for other credit, lenders will factor in this liability — potentially reducing what they can borrow.
JBSP is a specialist product. Fewer lenders offer it than standard mortgages, and criteria vary significantly. Using a broker who knows the JBSP market is essential to get the best rate.
When the buyer's income grows enough to stand alone, they can apply to remove the helper from the mortgage. This requires a full remortgage application and is subject to lender approval at that time.
JBSP is not offered by every lender. A whole-of-market broker will identify which lenders accept JBSP applications, match your specific circumstances, and find the most competitive rate available.
The buyer and helper will both need to provide proof of income (payslips, tax returns), bank statements, ID, and proof of address. Lenders will assess affordability based on the combined income profile.
Before making offers on properties, get an AIP so you know exactly what you can borrow. Your broker will handle this directly with the lender.
Your solicitor will handle the conveyancing and make sure the title deeds are drawn up correctly — with only the buyer named as the legal owner, regardless of how many are on the mortgage.
Agree upfront how long the helper intends to be on the mortgage and what the plan is for removing them. A clear timeline protects both parties and gives the buyer a goal to work towards.
Fee free advice • Whole of market access • JBSP specialists • FCA regulated
Your home may be repossessed if you do not keep up repayments on your mortgage. There may be a fee for mortgage advice. The actual amount you will pay will depend on your circumstances. The fee is up to £995 but typically we are fee free. Alexander Southwell Mortgage Services Ltd is authorised and regulated by the Financial Conduct Authority (FCA no. 1011890).
