Joint Borrower Sole Proprietor (JBSB) Mortgages

The UK property market has always been challenging for first-time buyers. On average, a first-time buyer needs a deposit of £30,000 and a 4.75 x salary lending cap to buy their dream home. Initiatives like a joint borrower sole proprietor (JBSP) mortgage make things a little more manageable.

If you are a first-time buyer or home mover, JBSP mortgages let your parents, partner or friend step in and help you get the mortgage you need. They use their income muscle, and you get to be the sole owner of the property.

JBSP mortgages are popular with first-time buyer purchases and home movers, too. While they are only getting more accepted with time, it is important to understand them in detail before making a final decision.

What is a joint borrower sole proprietor mortgage?

A joint borrower sole proprietor mortgage is an arrangement where multiple people can be named on the mortgage, but only one or two people legally own the property. You can have up to 4 people on your mortgage, while only 1-2 name stays on the property deeds.

Here, the “joint borrower(s)” are the supporting parties legally responsible for your mortgage. You are the “sole proprietor” who owns the property. In most cases, the joint borrowers are parents or close family members of the proprietor.

JBSP is an income booster mortgage. It bridges the gap between your income and the property’s cost. Many first-time buyers in the UK struggle with saving up for deposits or qualifying for mortgages based on their incomes. A JBSP mortgage resolves these issues. Those homeowners looking to move to a new property with their partner or family who is a first-time buyer can use JBSB and benefit from stamp duty relief.

Also, do not confuse JBSP with these family-assisted mortgage products:

• Joint mortgage: This mortgage involves multiple applicants, all of whom also own the property.
• Guarantor mortgage: This involves a guarantor who does not pool their income with yours. They step in only if you default.
• Family springboard: Here, family members offer a 10% cash deposit as security in a linked savings account.

The table below summarises the differences between JBSP, joint, and guarantor mortgages:

How does a JBSP mortgage work?

A JBSP mortgage has a two-party structure. The Land Registry deeds only have the sole proprietor’s name. They have the right to sell, renovate, or decorate the property.

The joint borrowers act as a financial backup. They are on the mortgage contract, making them responsible for making monthly repayments. However, they have no claim on the property or any future capital gains.

Here is a worked example to explain this better:

Suppose you are a first-time buyer with an income of £35,000. You want to buy a £280,000 flat, for which you have saved a £25,000 deposit.

If you go for solo borrowing, mortgage lenders in the UK are likely to lend you a maximum of £157,500 (based on the general 4.5x income multiple). Even with your deposit, you will be £97,000 short.

Now, suppose your family member or partner earns £55,000 and has a small remaining mortgage on their own home or no mortgage.

If you both approach a JBSP mortgage lender, they will combine your income (a total of £90,000) and lend you enough as a JBSP mortgage. Always remember, lenders will run all the income and outgoing on all the applicants, including their current mortgage debt.

As a result, you can easily secure the £255,000 you need.

It is important to note that the debt in a joint borrower sole proprietor is not solo. All parties named in the mortgage contract are jointly responsible for the monthly repayments.

Who can be a joint borrower?

Parents or sibling or partners are the most common joint borrowers. However, the 2026 UK property market is quite flexible.

These parties are eligible to become joint borrowers in a JBSP mortgage:

• Family members (aunts, uncles, siblings, and even step-relations)
• Non-relatives (a few lenders accept applications with close friends or long-term partners)

Irrespective of who the joint borrowers are, mortgage lenders require them to be UK residents for tax purposes. You should also take into consideration the age caps enforced by most lenders. Generally, lenders require borrowers to be 70 or 75 by the end of the mortgage term.

Benefits of a JBSP mortgage

Here is why the popularity of joint borrower sole proprietor mortgages is steadily increasing:

Benefits for the sole proprietor:

• Their affordability immediately increases, qualifying them for a bigger mortgage and better property.
• They have full control over the property and what to do with it (renovation, sale, etc.).
• They get to retain their first-time buyer status for tax benefits (like stamp duty surcharge).
• 100% of the property’s growth belongs to them.

Benefits for the joint borrowers:

• No need to liquidate their savings or take out a loan for a cash gift (especially for family members).
• No Capital Gains Tax liability when the property is sole (as they are not legal owners).
• No need to pay an additional 5% home surcharge, which is generally applicable when someone who already owns a property buys another one.

Major risks and drawbacks of a JBSP mortgage

Here is why all parties involved in a JBSP mortgage should be careful before making an application:

Risks and drawbacks for the sole proprietor

• They have a limited choice of mortgage lenders (only 15% of them offer a true JBSP product).
• The interest rates can be a little higher due to complex applications.
• They cannot remove the joint borrowers easily until they prove they can afford the mortgage independently.

Risks and drawbacks for joint borrowers

• They are at a credit risk at all times (if the sole proprietor misses payments).
• Remortgaging or investing in a new property becomes difficult (lenders see a JBSP mortgage as a full debt commitment).

Eligibility and lending criteria for a JBSP mortgage

Lenders analyse these eligibility and lending criteria to qualify borrowers for JBSP mortgages:

• Maximum LTV: Typically 95%
• Minimum deposit: 5% (can go up to 10%, too)
• Maximum borrowers: 4
• All borrowers should be credit-checked
• All borrowers’ income and debts combined for affordability
• Minimum income: £15,000 to £25,000 across borrowers
• Maximum age: 70 to 80 by the end of the mortgage term
• Borrowers need to have independent legal advice
• The Sole proprietor should live in the property

An experienced Fee Free Mortgage Broker can help you to understand this better.

Which UK lenders offer JBSP mortgages?

JBSP lenders in the UK can be classified under two main categories: mainstream lenders and specialist building societies.

Popular mainstream lenders include:

• NatWest
• Accord Mortgages
• Hinckley & Rugby

Popular specialist building societies include:

• Skipton Building Society
• Family Building Society
• Bath Building Society
• Suffolk Building Society
• Loughborough Building Society
• Darlington Building Society
• Mansfield Building Society

Note that many JBSP mortgage lenders in the UK are broker-only. They require their clients to work with brokers to approve and process their applications.

Costs and stamp duty on JBSP mortgages

Only the sole proprietor is liable to pay the stamp duty. This is an advantage for joint borrowers as they won’t need to pay an additional 5% stamp duty surcharge (even if they already own a property).

Also, if the sole proprietor is a first-time buyer, they need not pay a stamp duty land tax on properties up to £425,000.

Apart from stamp duty, the major costs associated with a JBSP mortgage include:

• Mortgage arrangement fees (up to £1,999).
• Valuation fees
• Legal fees
• Broker fees (unless you work with fee-free mortgage brokers)

The valuation, legal, and broker fees are the same as standard mortgages.

Step-by-step JBSP application process

While the precise process depends on your circumstances, here are the steps typically included in the JBSP process:

1. Consult a mortgage broker.
2. The broker will check all parties’ payslips, SA302s, and credit reports.
3. Prepare a Decision in Principle.
4. The lender’s surveyor will value the property.
5. The lender will make a final offer.
6. Get legal advice with the joint borrowers and sign a liability waiver.
7. Once you accept, your solicitor will oversee the transfer and registration.
8. The funds are released, and you can move into your new house.

Why work with a mortgage broker for a JBSP mortgage?

Most JBSP mortgage lenders in the UK require you to work with a broker. As a small percentage of lenders offer JBSP products, an experienced broker will help you find suitable offers and lenders. If you’re based in London, our JBSP mortgage broker London can review your eligibility within 24 hours.

At MariannaFS, fee-free mortgage brokers have the expertise to work with lenders like NatWest, Accord, Family BS, Skipton, and more.

Our fee-free mortgage brokers will help you find the right JBSP deals and guide you throughout your application journey.

Call us on 02080902043 or send us a WhatsApp message for a free JBSP affordability comparison call.

Frequently asked questions

Will a JBSP mortgage affect my parents’ ability to remortgage their home?

Yes, a JBSP mortgage is seen as a proper debt commitment. The repayment will be deducted from their overall affordability.

Can I use JBSP for a buy-to-let property?

Generally, no, you cannot. This mortgage is almost exclusively for residential properties.

Are joint borrowers required to live in the house?

No, they are not required to live in the purchased property, but if they want, they can.

What if a joint borrower dies?

As with most mortgages, the remaining borrower(s) and the sole proprietor become responsible for the debt. Always make sure that having enough mortgage cover in place.