If you have spent any time navigating the current UK Property Market, you may have felt the sinking feeling due to the unaffordability issues. You have the deposit saved, you have a solid career, and you have found the perfect home. But then comes the affordability check. The lender’s calculator spits out a number that falls heartbreakingly short of the asking price.

You are not alone in this frustration. Recent data suggests that a staggering number of adults currently living with parents cannot afford to buy a typical first-time buyer home in their local area based on their own finances alone. The gap between what you earn and what houses cost has never felt wider.

But what if you didn’t have to bridge that gap alone? At Kingsgate Finance, we often find that clients are unaware of a powerful tool designed specifically for this dilemma. It is technically known as a Joint Borrower Sole Proprietor (JBSP) mortgage, but we prefer to call it the Income Booster Mortgage. It might just be the secret weapon you need to unlock the door to your new home.

What Exactly Is an Income Booster Mortgage?

In simple terms, an Income Booster Mortgage allows you to add someone else’s income to your mortgage application to increase your borrowing power, without adding them to the title deeds of the property.

Traditionally, if you needed help from a parent or partner to afford a loan, you would take out a joint mortgage. This meant you both owned the property legally. With a JBSP mortgage, the structure is decoupled:

• The Proprietor (You): You are the sole legal owner. You hold the title deeds and build the equity.
• The Borrowers (You + Boosters): Up to four people can be named on the mortgage. Everyone is responsible for the repayments, meaning the lender considers the collective income of the group rather than just yours .

This structure fundamentally shifts the Mortgage Affordability calculation. Instead of relying on a standard 4.5x multiple of your salary, lenders can use the combined financial strength of your family to sanction a much larger loan.

What do you need to consider on an Income Booster Mortgage?

1. Choosing the Right Booster– Most commonly, boosters are parents helping their children get onto the property ladder. However, the criteria are evolving. Many lenders now accept siblings, grandparents, and even friends as income boosters. 

2. The Tax Advantage: Navigating Stamp Duty – On a standard joint mortgage, everyone would be classed as owner and if anyone has a property beforehand then it would trigger a 5% Stamp Duty Land Tax (SDLT) surcharge on the entire purchase price.

On JBSP, the boosters are not named on the deeds, they are not technically purchasing the property. Therefore, the transaction avoids the additional property surcharge. Furthermore, it preserves the boosters’ first time buyer relief status, provided they have never owned a home before.This structural nuance can save families tens of thousands of pounds in upfront taxes.

3. The Exit Strategy – An Income Booster is rarely intended to be a permanent arrangement. It is a temporary bridge. Once their financial position improves whether through salary increases, paying down other debts, or an inheritance the primary owner eventually can take over the full mortgage. 

Key benefits

In the traditional method, parents or family members would provide a lump sum to support the deposit to qualify within the mortgage affordability range. But the Income Booster Mortgage solves this by leveraging income rather than savings.

• Increased Borrowing Capacity: By aggregating incomes, a buyer could boost their borrowing capacity massively if supported by earning parents and friends 
• Keep Savings Intact: Parents can support their children without depleting their retirement savings or liquidating assets for lump sum. 

The Risks

• Joint and Several Liability: This is the legal term you must understand. Even though the booster does not own the home, they are 100% liable for the debt. If the homeowner misses a payment, the lender can pursue the booster for the full amount. This can impact the booster’s credit file and their ability to borrow money for themselves in the future
• No Beneficial Interest: Unless a specific legal side-agreement (like a Declaration of Trust) is drawn up, the booster has no legal claim to the property or its future equity growth, despite helping to pay for it.
• Independent Legal Advice (ILA): Because of the risks involved for the non-owner, lenders strictly require the booster to receive Independent Legal Advice before signing. This ensures they fully understand they are taking on a debt without receiving an asset.

Conclusion

The Income Booster Mortgage is sophisticated, tax-efficient, and incredibly effective for the right borrower. It allows you to leverage the collective strength of your family unit to navigate a hostile housing market. However, criteria vary wildly between lenders. Some cap the mortgage term based on the parents’ age (often 75 or 80), while others are more flexible. Some allow boosters to live in the property; others strictly forbid it. As for boosters, they need to be absolutely sure who they are supporting, since they will be legally liable to pay the repayment if the buyer does not comply with the repayment schedule. 

So if used wisely then Income Booster Mortgage can be a huge leverage to get on the property ladder. It is one of Kingsgate Finance’s expertise so if you would like to discuss it further then book your free initial consultation.   

Frequently Asked Questions (FAQ)

Q: Do my parents (the boosters) have to be on the title deeds?

A: No. In a JBSP mortgage, the boosters are named on the mortgage application but not on the title deeds. This means they do not legally own the property.

Q: Will my parents have to pay Stamp Duty?

A: Generally, no. Because the boosters do not acquire a legal interest in the property, they usually do not trigger the Stamp Duty surcharge for additional properties, provided the sole proprietor (you) does not already own a home. 

Q: Does the booster have to live in the property?

A: This depends on the lender. Many lenders require the booster not to live in the property (non-occupying borrower), but some lenders also allow boosters to reside there subject to specific criteria.

Q: Can I remove the booster (family and friends)  from the mortgage later?

A: Yes. Once your income has increased enough to support the mortgage on your own, you can apply to refinance or transfer the mortgage into your sole name.

Q: Is there an age limit for the income booster?

A: Yes. Lenders usually have a maximum age limit for the end of the mortgage term, typically between 75 and 80. If your boosters are older, this might require you to take a shorter mortgage term, which increases monthly repayments.