Joint Borrower Sole Proprietor Mortgages Explained

A joint borrower sole proprietor (JBSP) mortgage has two or more people on the mortgage but only one, or a couple, on the property’s title. The extra borrowers, usually parents, add their income so the lender will lend more. They do not own any part of the home.

It has become the most common way for parents to help with affordability, because fewer lenders now offer traditional guarantor mortgages.

How a JBSP mortgage works

• Everyone applies together. The lender assesses the income and commitments of every borrower.
• Only you own the home. You are registered at HM Land Registry as the owner. The supporting borrowers have no share of the property.
• Everyone owes the whole debt. All borrowers are jointly and severally liable. If payments stop, the lender can pursue any of them for the full amount.
• You live there, they do not. Lenders normally require the owner to occupy the property.

How much more could you borrow?

On your own, a £30,000 salary might support borrowing of around £135,000 with a lender using 4.5 times income. With a parent on the application, the lender looks at both incomes and both households’ outgoings, including any mortgage the parent already has. That can lift the loan considerably, but the result depends heavily on the parent’s own commitments and age.

Age matters. Lenders set a maximum age for the oldest borrower at the end of the term, often somewhere between 70 and 85. If a parent is 55, the mortgage term may be shortened, which raises the monthly payment. Some lenders will assess a parent’s income only up to their expected retirement age.

Use our affordability calculator for an initial estimate, then we can check how specific lenders would treat your family’s income.

Who is it suitable for?

• First-time buyers whose income is not quite enough on its own, with a parent or relative who can support the application.
• People early in their careers whose income is likely to rise, who plan to remortgage into their own name later.
• Buyers with variable income, such as bonuses or commission, where a supporting borrower adds stability.
• Movers buying in a more expensive area, where their income falls short.

It is usually not suitable if the supporting borrower wants a share of the home, has poor credit, is close to retirement, or could not cope with paying the mortgage themselves if they had to.

Stamp Duty and tax

Because the supporting borrowers are not on the title, they are not buying the property. For Stamp Duty, that usually means:

• No higher-rate surcharge for the parents, even if they already own a home. On a joint mortgage where parents also went on the title, the purchase could count as an additional property for them.
• First-time buyer relief may still be available if you qualify on your own. See who counts as a first-time buyer.
• No capital gains tax for the parents when the home is sold, because they never owned it.

If parents contribute to the payments or the deposit, those contributions may be gifts for inheritance tax purposes. Ask your conveyancer or a tax adviser to check your circumstances.

The risks your family should understand

• Full liability, no ownership. A supporting borrower is liable for every pound of the mortgage but has no claim on the home. If the relationship breaks down, they could be left with the debt and nothing to show for it.
• Their own borrowing. The mortgage appears on their credit file and counts in future affordability checks, which may affect their own remortgage, a move or a buy-to-let purchase.
• Missed payments affect everyone. Late payments are recorded on all borrowers’ credit files.
• Fewer lender choices. Not every lender offers JBSP, and those that do have rules on who can be a supporting borrower, how many borrowers can apply and their ages.

Many lenders require supporting borrowers to take independent legal advice. Even where it is not required, it is sensible, and a written family agreement setting out who pays what, and what happens if circumstances change, can prevent problems later.

Taking your family off the mortgage

The aim is often to remortgage into your sole name once your income has grown. That needs you to pass a lender’s affordability checks on your own at that time, so plan for it rather than assuming it will happen. Our remortgage guide explains the process.

How JBSP compares with other family help

Option	Family member owns part of the home?	Family member liable for the mortgage?	Boosts what you can borrow?
Joint borrower sole proprietor	No	Yes, for the whole loan	Yes
Joint mortgage with parents on the title	Yes	Yes	Yes, but Stamp Duty surcharge may apply
Guarantor mortgage	No	Only if you do not pay	Yes
Gifted deposit	No	No	No, but a bigger deposit can widen choice
Family Springboard	No	Savings at risk	Can allow a smaller deposit

Our first-time buyer mortgage guide covers every option side by side.

JBSP mortgage FAQs

Speak to us with your family

We regularly help parents and first-time buyers decide between a JBSP mortgage, a guarantor mortgage and a gifted deposit, so everyone understands what they are signing up to. Your initial consultation is free.