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Income Boost


Increase what you can borrow with an Income Boost

Add some or all of a guarantor’s earnings to your household income to boost your buying budget, without them having ownership of the home.

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British Bank awards 2023 Best Mortgage Broker winner

Discover how much you can really borrow.


First-time buyers, movers & remortgagers


Average £82,000 boost to affordability


Requires the support of a guarantor

How does it work?

Also known as Joint Borrower Sole Proprietor mortgage (JBSP), an Income Boost is a way of increasing what you can afford to borrow for a mortgage with the help of a loved one. By adding some or all of their earnings to your household income, a lender will allow you to borrow more.

You’ll still be the sole owner of the property, so there aren’t tax implications for you or your Booster. They also don’t need to contribute to monthly repayments, but if you are unable to pay, they’ll be required to step in.

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Why Tembo?

We help buyers, movers and homeowners discover how they could boost their affordability in 3 simple steps. It’s why we’re the UK’s Best Mortgage Broker.


Things to consider

All mortgages have risks and benefits. Here are some key things you should know about before applying for an Income Boost


What are the benefits?

Increase your borrowing power

With an Income Boost, you can combine up to four income sources to significantly increase your buying budget. So there’s no need to compromise on your dream home, or spend decades savings up a house deposit.

A stepping stone to independence

If you can afford the mortgage by yourself in the future, you can remove your Booster from the mortgage. In this way, an Income Boost can be a temporary ‘leg up’ to help you get on the ladder.

Your Booster won’t be out of pocket

Your Booster doesn’t need to offer up cash savings or investments to help you buy. As long as you make your repayments each month, they won’t have to contribute financially.

First-time buyer stamp duty relief is not affected

Your Booster won’t be listed on the deeds of your home. So any first-time buyer stamp duty relief you might be eligible for isn’t impacted, and your Booster’s tax position won’t be affected either.

Risks and considerations

Everyone on the mortgage is liable for the debt

If you cannot make your repayments, your guarantor will be required to step in. If no one makes the payments, this will impact the credit history of each applicant and could result in your home being repossessed.

Your Booster’s age could impact your repayments

Most lenders cap the mortgage term based on the age of the oldest applicant. If your Booster is over the age of 60, this means your mortgage term could be shorter, and therefore the monthly repayments would be higher.

All applicants will go through affordability checks

We need to ensure the mortgage is affordable for all applicants. Our assessment includes providing proof of income, outgoings, identification and a credit check.

Your Booster will have no legal rights to the property

As a guarantor, your Booster will not be a co-owner of the property and does not have an equity share, so they won’t benefit if the property’s value increases. If your Booster is interested in co-buying, explore a Dynamic Income Boost.

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Frequently asked questions

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The application process

Get into your very own home in 4 simple steps


Make a Tembo plan

In under 10-minutes we’ll check your eligibility for an Joint Borrower Sole Proprietor mortgage as well as our other buying schemes. Plus you’ll get a personalised mortgage recommendation including interest rates and repayments.


Talk to an expert

Book a call with our mortgage experts to complete the qualification process. We’ll cover any questions you might have about Joint Borrower Sole Proprietor mortgages and any other schemes, and collect more information about you.


Apply for a mortgage

Your dedicated advisor will undertake full affordability with you & your Booster, and prepare an application with your chosen lender. As part of the application process, we’ll help to arrange for your Booster to get Independent Legal Advice.


Make home happen

During the conveyancing process, we’ll liaise with the seller and your solicitors to ensure a smooth purchase. We’ll also provide a free protection review. Your case manager will be on hand all the way through to move in day!

Other schemes you might like

Explore our other buying schemes to discover alternative ways to buy.

See all schemes

On your own

Deposit Unlock

Purchase a new build home from a participating home builder with just a 5% deposit.

See details

With a guarantor

Dynamic Income Boost

Add some or all of a guarantor’s earnings to your income to boost your budget & track their support.

See details

Family remortgage

Deposit Boost

Unlock a gifted deposit from a loved one’s property to create a house deposit from scratch or top up your existing deposit.

See details

Learn more

Confused about mortgages? Read our guides for expert tips on saving, buying and the market.

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Other mortgage schemes

You can be snug in your very own home in 4 simple steps


Standard Mortgage

Right to buy

Self Employed

Tier 2 Visa

Deposit Unlock

Armed Forces Help To Buy

Shariah mortgage

Increase your affordability

With a guarantor