Joint Borrower Sole Proprietor Mortgages
A Joint Borrower Sole Proprietor (JBSP) mortgage — often referred to as a Mortgage Boost and sometimes compared to a guarantor-style mortgage — allows you to increase your borrowing by adding another person to the mortgage application without giving them ownership of the property.
This type of mortgage is particularly popular with first-time buyers and younger buyers whose income alone may not meet lender affordability criteria. A supporting borrower, often a parent or close family member acting in a guarantor-style role, joins the mortgage to strengthen the application while the property remains in your name only.
Because the supporting borrower is not named on the title deeds, they have no legal ownership of the property. This can help avoid additional Stamp Duty charges that may apply when someone already owns another home.
How Does a JBSP (Mortgage Boost) Mortgage Work?
A JBSP mortgage separates who borrows from who owns the property, which is why it’s often seen as a modern alternative to a traditional guarantor mortgage.
All borrowers are assessed on income, credit history and affordability, but only one person is listed as the legal owner on the property deeds.
Key points to be aware of:
- One person is named as the sole owner of the property
- One or more supporting borrowers (guarantor-style applicants) are added to the mortgage only
- Everyone named on the mortgage is jointly responsible for repayments
- Once affordability improves, the supporting borrower can often be removed through a remortgage or product switch
Who Is a JBSP / Guarantor-Style Mortgage Suitable For?
A Joint Borrower Sole Proprietor mortgage may be suitable if you are:
- A first-time buyer needing a mortgage boost to meet affordability checks
- A parent looking to support a child in a guarantor-style arrangement without owning part of the property
- Family members who want to provide financial support while keeping ownership simple
This type of mortgage is ideal for buyers who need help with affordability but want to avoid the complexity and Stamp Duty implications often associated with traditional guarantor mortgages.
Example: Using a Mortgage Boost to Buy Your First Home
Emily is buying her first home for £350,000, but her income alone isn’t enough to secure the required mortgage. Her father agrees to support the application as a joint borrower in a guarantor-style role.
His income boosts the overall affordability, allowing Emily to buy the property in her own name without adding her father to the title deeds.
Tell us about your mortgage requirements
Speak to a JBSP and Guarantor Mortgage Specialist
JBSP mortgages and guarantor-style arrangements vary significantly between lenders, so expert advice is essential.
At FPG Mortgages, our specialist brokers will help you decide whether a JBSP mortgage, mortgage boost or alternative guarantor solution is right for you — and structure the application correctly from the outset.