Your home is probably the most valuable thing you own. After years of mortgage payments and property price growth, you may be sitting on a six-figure sum of equity — and watching your adult children struggle to get a foot on the housing ladder. The temptation to unlock that value and help them is entirely understandable. But this is one of those decisions where good intentions, without professional structuring, can quietly devastate your retirement plans, your tax position, and even your family relationships. Before you contact your lender, read this.
The Two Main Routes: Cash Gift or Guarantee
UK homeowners typically help family in one of two ways. The first is drawing equity directly — remortgaging or taking a further advance to release cash, which is then given or lent to a child. The second is acting as a guarantor or joint borrower on the child’s own mortgage, using your property as additional security. Both routes carry serious legal and financial consequences that most families never properly address until something goes wrong.
If you draw equity, you are increasing your own mortgage debt. You will pay interest on that additional borrowing for potentially decades. If your child cannot or does not repay you, the bank does not care — the debt is yours, secured against your home. If you act as guarantor, you may not hand over any cash at all, but you are promising the lender that if your child defaults, you will cover the shortfall. In either case, your home is on the line.
Joint and Several Liability: The Fact Most Families Get Wrong
If you are added to your child’s mortgage as a joint borrower — a common arrangement where parents help children pass affordability checks — you need to understand joint and several liability. This means the lender can pursue either borrower for 100% of the outstanding debt, not just half. If your child stops paying, the lender can come after you for the full amount. There is no informal “my share” and “their share” in the eyes of the lender. This single fact changes the entire risk calculus and is the most commonly misunderstood element of family property arrangements in the UK.
Equally important: that mortgage will appear on your credit file and will be stress-tested at its full value when you apply for any future borrowing. If you want to remortgage your own home, move, or borrow for any other purpose, lenders will treat you as though you personally owe the entire joint mortgage balance. Your borrowing capacity could be severely impaired for years.
The SDLT Surcharge Trap
Here is where well-meaning help gets expensive fast. If either person named on the purchase already owns a residential property anywhere in the world, the 3% Stamp Duty Land Tax higher-rate surcharge applies to the entire purchase price. So if a parent who owns their own home is added to a child’s mortgage as a joint borrower, the child — even if they are a genuine first-time buyer — loses their first-time buyer SDLT relief, and the purchase attracts the surcharge on every penny. On a £300,000 property, that is an additional £9,000 payable at completion. This catches families off guard with depressing regularity.
Some lenders offer “joint borrower, sole proprietor” mortgages (sometimes called JBSP), where the parent is on the mortgage but not on the title deeds. These can avoid the SDLT surcharge, but they come with their own complexities — the parent has full liability but no ownership interest. Take legal advice before committing.
Tenancy in Common, Not Joint Tenancy
If a parent and child do end up co-owning a property, the default legal structure matters enormously. Joint tenancy means both parties own the whole property equally, and on death the survivor automatically inherits the deceased’s share (the right of survivorship). For non-married co-owners — which includes parents and children — this is almost always the wrong structure.
Tenancy in common allows each party to hold a specified share (say, 75/25), and each share can be left to whomever they choose in their will. This is critical for inheritance tax planning and for protecting each party’s contribution. Without tenancy in common, a parent who contributed 80% of the deposit could find their estate has no legal claim to that money if the property automatically passes to the child on death — or vice versa.
The Declaration of Trust: Non-Negotiable
A Declaration of Trust (also called a Deed of Trust) is the single most important document in any family co-ownership or equity-sharing arrangement. Without one, courts and HMRC will default to assuming equal beneficial shares regardless of actual financial contributions. This document should specify:
- Each party’s percentage beneficial interest
- Whether unequal contributions are treated as loans or equity adjustments
- What happens on sale — including a right of first refusal and a clear buy-sell mechanism with independent valuation
- An exit timeline and process if either party wants out
- Occupancy rules, shared expense responsibilities, and renovation consent thresholds
- How disputes will be resolved before they reach court
Execute this as a deed, not a simple contract. Obligations in a deed carry a 12-year limitation period for enforcement, compared with just 6 years for a standard contract. This difference matters enormously if disagreements surface years down the line.
TOLATA: The Forced Sale Risk Nobody Mentions
Under the Trusts of Land and Appointment of Trustees Act 1996 (TOLATA), either co-owner can apply to court to force a sale of the property, even if the other party objects. This is not a theoretical risk. If relationships break down — through divorce, financial difficulty, or simple family disagreement — a TOLATA application can compel a sale at the worst possible time. A well-drafted Declaration of Trust can include provisions to manage this risk, but it cannot override the court’s ultimate jurisdiction. Families need to go into these arrangements with eyes open.
Tax Consequences: CGT, IHT, and the Gift Trap
Capital Gains Tax: Principal Private Residence Relief only applies to the property that is genuinely your main home. If a parent co-owns a child’s property but lives elsewhere, their share of any gain on sale is fully chargeable to CGT. At current rates of up to 24% on residential property gains, this can be a substantial and unwelcome bill.
Inheritance Tax: If a parent gives equity to a child and survives seven years, the gift falls outside their estate. If they die within seven years, taper relief may reduce the IHT liability, but the gift is still potentially chargeable. Where a parent gifts equity but continues to benefit from it — for example, living rent-free in a jointly owned property — HMRC may apply the gift with reservation of benefit rules, meaning the asset remains in the parent’s estate for IHT purposes regardless of how long ago the gift was made.
The gift versus loan distinction is also critical. If you provide cash to a child and do not document it as a loan, HMRC and the courts may treat it as a gift. Mortgage lenders routinely require a “gifted deposit” letter confirming the money is not repayable. Once you sign that letter, you have legally confirmed you have no claim to that money. If you actually intend for it to be repaid, you need a formal loan agreement — and you should not sign the gifted deposit letter.
Protecting Your Own Retirement
Increasing your mortgage in your fifties or sixties to help your children is a decision that directly competes with your retirement security. Lenders will assess whether you can sustain repayments into retirement, and many impose maximum age limits at the end of the mortgage term. If you draw £80,000 of equity at age 58, you could still be repaying it at 78. Run the numbers honestly: can you afford this if your pension income is lower than expected, if you need care, or if property values fall?
The Bottom Line: What to Do Before You Sign Anything
Helping your family with your home equity is generous and often transformative. But it demands the same rigour you would apply to any significant financial transaction. At minimum, take these steps: instruct a solicitor to prepare a Declaration of Trust executed as a deed; get independent mortgage advice for both parties; model the SDLT implications before anyone is named on title; confirm the CGT and IHT position with a tax adviser; and have an honest conversation about what happens if things go wrong. The families who protect themselves properly are the ones whose generosity actually works — for everyone.
Disclaimer: The information provided in this article is for informational purposes only and should not be considered financial or legal advice. Property and lending laws in the United Kingdom vary and may change over time. We always recommend consulting with a qualified solicitor and mortgage broker before entering into a property purchase or financial arrangement with another party.
