Buying a property can be challenging, particularly if it’s your first time and you don’t meet all the affordability requirements on your own. A joint borrower sole proprietor mortgage can provide a practical solution by allowing family members to support the mortgage application without becoming legal owners of the property.
Some UK lenders, including Barclays and NatWest, offer mortgage products designed specifically for this arrangement. However, understanding how these mortgages work and which option is most suitable often requires professional advice.
In this guide, we explain how JBSP mortgages work, which lenders offer them, and why speaking to a mortgage broker first can help you make the right decision. If you’d like advice tailored to your own situation, book a call today with Simmonds Mortgage Services.
Are JBSP mortgages easy to get approved for?
While a JBSP mortgage can make it easier to get onto the property ladder sooner, it doesn’t mean you’ll be automatically approved for one.
With a joint borrower sole proprietor mortgage, only one person is the legal owner listed on the property deeds. However, additional borrowers, who are usually family members (parents, grandparents, older siblings), are also added to the mortgage application to boost the combined income used in the lender’s affordability assessment.
This means lenders look at more than just the sole proprietor’s income. They also include the income, credit history, and financial commitments of all supporting borrowers.
While this can significantly increase your borrowing power, lenders will still apply their eligibility criteria carefully. They want to be confident that everyone named on the mortgage can comfortably manage the monthly repayments if circumstances change.
Most lenders offering JBSP mortgages will want to check:
- The credit score of all borrowers
- The combined income available to cover the mortgage repayments
- The maximum loan-to-value (LTV) on the property
- The mortgage term as well as the ages of any supporting borrowers
- The legal implications for everyone involved
Because each lender’s affordability criteria are different, one lender may approve an application that another declines. This is why it’s always recommended to speak to a mortgage broker early on. Our job is to help you get into the best possible place before sending off an application.
It’s important to remember that all borrowers are jointly responsible for the mortgage. If mortgage repayments are missed, the lender can pursue any borrower on the mortgage for payment.
Which UK lenders offer joint borrower sole proprietor mortgages?
Several UK lenders offer JBSP mortgage products designed to support buyers who need financial assistance from family members.
Some of the most well-known lenders offering JBSP mortgage products include:
- Barclays
- NatWest
- Metro Bank
- Skipton Building Society
- Gen H
However, each lender has its own criteria and eligibility rules. These may include:
- Age limits for supporting borrowers
- Maximum mortgage term
- Affordability requirements
- Credit checks
- Property eligibility rules
And because each lender is different, it’s important to explore all options before making a decision.
Let’s take a look at some of the top lenders offering JBSP mortgages:
Barclays, Mortgage Boost
Barclays offers a JBSP product called Mortgage Boost, designed to help buyers who have enough income to manage mortgage payments but fall slightly short on affordability.
With Mortgage Boost, a family member or friend can join the mortgage as a joint borrower without becoming a legal owner of the property. This allows the main borrower to retain sole legal ownership, which can simplify matters such as Stamp Duty liability and future property ownership.
| Pros | Cons |
| Offered by a major high street bank | Age limits affect the mortgage term |
| Up to four borrowers can be added to the mortgage | Cannot be used with other special products or schemes |
| Available to first-time buyers and existing homeowners | |
| Can be used for buy-to-let mortgages | |
| Low deposit options | |
| Upper age limit of 80 |
NatWest, Family-Backed Mortgage
NatWest provides a family-backed JBSP mortgage that helps buyers move onto the property ladder sooner. With this product, friends, parents, or other family members can support the mortgage by joining as additional borrowers, while the buyer remains the sole proprietor listed on the property deeds.
NatWest assesses the combined income of all borrowers, which can increase the maximum loan amount available.
| Pros | Cons |
| Offered by a major high street bank | Maximum of two applicants (owner and non-owner) |
| Widely available and straightforward to apply for | Not available for buy-to-let |
| Suitable for first-time buyers but also existing homeowners | Cannot be used alongside the Shared Equity or Right to Buy schemes |
| Friends and family can support the application | Upper age limit of around 70 to 75 |
Metro Bank, joint borrower sole proprietor mortgage
Metro Bank also offers a joint borrower sole proprietor mortgage designed for buyers who need additional support to meet affordability requirements. This product is helpful for buyers with strong income potential but who don’t quite meet the lender’s eligibility criteria on their own. They can add up to four supporting borrowers to boost their affordability.
| Pros | Cons |
| Allows up to four people on the mortgage | Cannot be used on their “professional” mortgage ranges (e.g., for doctors, lawyers, and so on) |
| Can add non-relatives to the mortgage application | Application process can be longer |
| 5% deposits on houses and flats | |
| 10% deposits on newbuilds | |
| Gifted deposits are accepted | |
| Upper age limit of 80 | |
| Interest-only, repayment, and part and part options |
Skipton Building Society, Income Booster
Skipton Building Society offers a JBSP option called Income Booster, designed to help borrowers who have a stable income but need additional affordability support.
The product allows friends or family to join the mortgage without becoming a legal owner. This can help increase the maximum loan amount available while keeping the property under the sole legal ownership of the buyer.
| Pros | Cons |
| Flexible and accessible | Cannot be used with other first-time buyer schemes or discounted purchases |
| Allows up to four borrowers | Cannot be used for buy-to-let |
| Can add non-relatives to the application | Loan term is determined by the oldest applicant |
| 5% deposit options | |
| Can be used for house purchase or remortgage |
Gen H, Income Booster
Gen H offers a more modern take on the joint borrower sole proprietor mortgage with its Income Booster product. It’s designed for buyers who need support now but could afford the mortgage independently in the future.
Their “ejector seat” feature can help borrowers get a longer mortgage term and increase their borrowing potential if there’s evidence they can afford the mortgage in the future. The idea is that the supporting borrower is included on the mortgage on a temporary basis, with a planned point in the future where they are removed from the loan. But if the sole proprietor’s income increases sooner, the supporting borrower can be removed earlier.
| Pros | Cons |
| Accepts both family and non-family members | May involve more detailed affordability assessments |
| Allows up to five supporting borrowers | Criteria can be more case-specific than traditional banks |
| Supporting borrowers are removed later | Not suitable for all property types or scenarios |
| Supporting borrowers can help with monthly payments if they want | |
| Flexible approach compared to some high street lenders | |
| Low deposit options |
What do lenders look for when applying for a JBSP mortgage?
When applying for a joint borrower sole proprietor mortgage, lenders look closely at the finances of every borrower involved.
Credit checks
Lenders will perform credit checks on all borrowers listed on the mortgage. A strong credit score improves the likelihood of approval and access to better mortgage deals. If any borrower has a history of missed payments or poor credit, this could affect the application.
Your joint borrowing power
Lenders will assess the combined income of all borrowers, including salaries, bonuses, and other reliable income sources such as pensions and rental income.
Mortgage payment affordability
Alongside income, lenders also consider existing financial commitments of each person on the mortgage application. This includes any existing mortgage payments, personal loans, credit card debt, and personal living expenses like household bills.
Age limits
Some JBSP products have strict rules for older co-borrowers. They may set a maximum age limit and base the loan terms on the oldest borrower. If the supporting applicant is close to retirement, lenders usually want to see proof of income after retirement.
Deposit
Lenders will want to see proof that the deposit is legitimate. Some flexible JBSP lenders accept gifted deposits from family members, and some even provide low-deposit mortgage products.
Why professional advice is important when choosing a JBSP mortgage
Joint borrower sole proprietor mortgages can be a brilliant way to get onto the property ladder sooner, but they are certainly not one-size-fits-all. Each lender approaches JBSP mortgages differently, from how they assess income to how they structure the mortgage term.
At Simmonds Mortgage Services, we work with JBSP cases regularly. We know which lenders are more flexible, how to present your application in the strongest way, and how to structure things so it works for both you and your family long term.
Working with an experienced mortgage broker like Simmonds means you benefit from:
- Access to lenders who suit your situation
- Understanding how much you can borrow and how it might impact your finances
- Dedicated support through the full mortgage process
- Understanding ownership, joint responsibility, and potential tax implications
- Feeling confident that you’re choosing the right mortgage
See how we helped a couple keep their family home by swapping them to a JBSP mortgage.
Find the right joint mortgage product with Simmonds Mortgages Services
At Simmonds Mortgage Services, we regularly help buyers and families explore joint borrower sole proprietor mortgage solutions. Our experienced brokers will review your finances, discuss your situation, and identify lenders who provide mortgage solutions suited to your needs.
Whether you are a first-time buyer, moving home, or helping a family member get onto the property ladder, we’ll guide you through the process and help you get the right mortgage.
Speak to Simmonds Mortgage Services today to explore your options.
