# What is a joint borrower sole proprietor mortgage?

> Quick answer · Last updated 4 July 2026

Canonical HTML: https://moneyguide.org.uk/answers/what-is-joint-borrower-sole-proprietor-mortgage/
Markdown mirror: https://moneyguide.org.uk/answers/what-is-joint-borrower-sole-proprietor-mortgage.md

## In short

A JBSP mortgage lets a family member (often a parent) join the mortgage application to boost borrowing power while only the buyer is named on the property deed — useful when the buyer's income alone is too low but the helper does not want ownership or second-home Stamp Duty.

The proprietor is solely on the title; the joint borrower is on the mortgage but not the deed. Lenders assess combined income for affordability but only the buyer owns the property.

The helper is jointly liable for the debt without ownership rights — a serious commitment. Not all lenders offer JBSP; specialist brokers know which do.

Alternatives include guarantor mortgages, gifting deposits, or waiting until income rises. Compare total cost and legal implications before proceeding.

## Related

- [Mortgage affordability calculator](https://moneyguide.org.uk/tools/mortgage-affordability-calculator/)
- [First-time buyer step-by-step](https://moneyguide.org.uk/mortgages/first-time-buyer-step-by-step/)
- [Loan-to-value explained](https://moneyguide.org.uk/mortgages/loan-to-value-explained/)

## Primary source

gov.uk/buying-a-home

---

Independent UK money guidance from [Money Guide](https://moneyguide.org.uk). Information only — not regulated financial advice.