Joint Mortgage, Sole Proprietor: How It Works and Why It Saves Tax

A Joint Borrower Sole Proprietor (JBSP) mortgage allows multiple people to be named on the mortgage (and therefore use their combined income for affordability purposes) while only one person is registered as the legal owner of the property at HM Land Registry.

The Most Common Use Case

The most common use of JBSP is a parent helping an adult child buy their first home. The child cannot borrow enough on their income alone, so the parent joins the mortgage to increase the borrowing capacity. However, the parent does not want to be an owner because:

• Being on the title would mean the purchase attracts the 3% additional dwelling SDLT surcharge (as the parent already owns a home)
• Being an owner could affect the child’s first-time buyer stamp duty relief
• The parent does not want (or need) an ownership stake

By being a joint borrower but not a proprietor, the parent’s income is counted, the child owns 100%, and first-time buyer SDLT relief is preserved (subject to HMRC’s rules).

How It Works

• All borrowers (both the child and the parent) are fully responsible for the mortgage payments
• Only the sole proprietor (the child) is on the title register at HM Land Registry
• Both borrowers undergo the lender’s affordability and credit assessment
• The property’s purchase price is based on combined income

The Stamp Duty Position

First-time buyer SDLT relief (0% on the first £300,000 in England) is available if the buyer is a first-time buyer and the property will be their only home. A parent who co-owns another property cannot be a proprietor without triggering the additional dwelling surcharge. As a JBSP borrower (not a proprietor), the parent does not affect the stamp duty position.

**Important:** HMRC’s rules on this area have been tested and can be complex. Always take specialist stamp duty advice before proceeding, particularly if the child has previously owned property.

Lenders That Offer JBSP

Not all lenders offer JBSP mortgages. Those that typically do include:

• Barclays (Family Springboard Mortgage)
• Bath Building Society
• Newbury Building Society
• Various specialist lenders

Terms vary significantly. A whole-of-market broker is essential for identifying the most suitable product.

Risks for the Joint Borrower (Parent)

The non-owner borrower takes on significant risk:

• **Full liability:** If the child cannot pay, the parent is fully responsible for the mortgage
• **Credit impact:** The mortgage appears on the parent’s credit file; it affects their own borrowing capacity
• **Relationship risk:** Financial entanglement can complicate relationships

The parent should take independent legal advice before entering a JBSP arrangement.

Exit Strategy

When the child’s income increases sufficiently, the parent can be removed from the mortgage by remortgaging in the child’s sole name. This requires the mortgage to pass affordability on the child’s income alone at that point.

Alternatives

• **Guarantor mortgage:** The parent guarantees the mortgage rather than being a co-borrower. Similar practical effect, different legal structure.
• **Declaration of Trust:** Parent makes a cash gift for the deposit, protected by a declaration that it is a gift (not a loan) to satisfy lender requirements.
• **Family offset mortgage:** Some lenders allow a family member to use their savings as collateral to reduce the child’s effective LTV without being on the mortgage.