Boost how much you can borrow

Joint Borrower Sole Proprietor mortgages

Can't borrow quite enough for the house you want? Your family could give your affordability an extra boost.

You could borrow more than you think with a 'Joint Borrower Sole Proprietor' (JSBP) mortgage. JBSP mortgages can be helpful for first time buyers who are buying alone, or are on a lower income.

How a Principality JBSP mortgage works

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Apply with up to four family members

Hands holding a heart
the income of all applicants

Hand putting a coin into an open palm
Borrow more
than if you applied alone

Keep sole ownership of your home

A family member’s name is added to your mortgage application. We can then take their income into account when working out how much you can borrow.

By doing this your family member agrees to pay your repayments if you can’t meet them (a bit like a guarantor mortgage). But unlike a guarantor mortgage, they aren't offering their own property or savings up as security against your loan.

Your family member won't own any part of the home you’re buying; it’s completely in your name. And they won't need to pay Stamp Duty or Land Transaction Tax

Example 1 

The house Charlie wants to buy costs £200k. But she can only borrow £170k for her mortgage.

Charlie applies for a JBSP mortgage with her mum. With her mum's income added to her mortgage application, Charlie can borrow the full £200k.

After a few years Charlie chooses to remove her mum from the mortgage.

Example 2 

James already owns his own place. His mum and dad have always rented.

James earns more than his parents and often helps them out with money and bills. They can't borrow enough to buy a home of their own.

To help them buy a home, they take out a JBSP mortgage with James. This helps boost the amount they can borrow.

Example 3 

Kai recently separated from her husband and he has moved out of the home they owned together.

She wants to take over the mortgage on her own, to stay living near her children's school. But with her income alone, she's unable to borrow enough.

Kai takes out a JBSP mortgage with her dad. Now she's able to afford to take over the mortgage. A few years later she takes her dad off the mortgage when she gets a promotion at work.

Are there any risks for the family member(s) helping you?

Your family member(s) should take independent legal advice and talk everything through with a mortgage advisor. Their solicitor should make sure they understand any risks of being named on your mortgage. Some key things to be aware of are:

  1. You pay the mortgage repayments - But if you can’t, your family member(s) agrees to do so for you. If nobody makes the repayments, it affects the credit of everyone on the mortgage.
  2. The home belongs to you - As they don’t own the home, they can’t force you to sell it.
  3. We take their affordability into account to boost how much you can borrow - This means they may not be able to borrow more on a mortgage themselves while they are on yours.

The important stuff

Will the family member(s) stay on your mortgage forever?

No; you can remove them when you’re ready. Your financial circumstances may change in the future. If your salary goes up, or once you've paid off a significant part of the mortgage you may feel ready to fully take on the mortgage yourself. A JBSP mortgage is a temporary affordability boost to get you on the ladder.

Who can you add to your mortgage application?

Family help comes in all shapes and sizes. You can get help with your mortgage affordability from: your spouse, grandparent, parent, sibling, or a legal guardian. Children and grandchildren can also help their parents or grandparents to buy.

Will the family member(s) have a claim on your home?

The home will legally belong to you alone. You’ve borrowed together (joint borrowers) but you’re the only owner (the sole proprietor).

If I'm boosting affordability, will I be able to afford the monthly repayments?

You're responsible for making sure you make your monthly mortgage repayments. We'll assess this together as part of your application. It's part of the usual affordability checks we carry out.

Our Joint Borrower Sole Proprietor mortgages

  Cyfradd gychwynnol Tan Then our standard variable rate, less a discount of 0.50% Until Yna'r gyfradd amrywiol safonol Y gost gyfan er mwyn cymharu Ffi cynnyrch Cashback  
MORGAIS CYFRADD SEFYDLOG 90% 6.00% 31/08/2026 7.10% 31/08/2029 7.60% 7.4% APRC £0 Nid oes cyfleuster arian yn ôl gyda'r cynnyrch hwn. More details
MORGAIS CYFRADD SEFYDLOG 90% 5.40% 31/08/2029 N/A N/A 7.60% 6.8% APRC £0 Nid oes cyfleuster arian yn ôl gyda'r cynnyrch hwn. More details


Ways to start your application

Our contact centre is open 9am to 5pm Monday to Friday and 9am to 1pm on Saturday and our branches are located across Wales and the borders, find a branch.

Start your mortgage enquiry online

Call us on 03303334002

Request an appointment at branch

  • 6ed cymdeithas adeiladu fwyaf y DU
  • Cymdeithas adeiladu gydfuddiannol, sy’n eiddo i’n 500,000 o aelodau ac yn cael ei rhedeg er eu lles
  • Dros 160 mlynedd o brofiad
  • Gofalu am werth dros £12 biliwn o asedau ein cwsmeriaid
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