Last reviewed: June 2026
TL;DR- A family offset mortgage links a family member's savings account to the borrower's mortgage - the savings reduce the mortgage balance on which interest is charged.
- The family member retains ownership of and access to their savings - the money is not given away and does not form part of the deposit.
- The family member earns no interest on the savings but benefits from not having to pay income tax on savings interest, because the benefit is delivered as reduced mortgage interest instead.
- Not all lenders offer family offset mortgages - availability is more limited than standard offset products.
How a Family Offset Mortgage Works
A family offset mortgage is a variant of the standard offset mortgage in which the savings account linked to the mortgage is held by a family member rather than the borrower. The family member - typically a parent or grandparent - places savings in a linked account with the mortgage lender. The balance of that savings account is deducted from the mortgage balance when calculating the interest charged each month. If the mortgage is £200,000 and the family member's linked savings total £50,000, interest is charged only on £150,000.
The family member's savings remain in their own account. They retain full ownership and can withdraw the money at any time, though doing so reduces the offset benefit immediately. They do not become a party to the mortgage, do not appear on the property title, and are not liable for the mortgage debt.
The Benefit to the Borrower
The borrower benefits from reduced monthly interest charges. Depending on the size of the family savings relative to the mortgage, this can substantially reduce the total interest paid over the mortgage term or shorten the effective term. The benefit is greatest when the linked savings are a high proportion of the outstanding mortgage balance.
For a first time buyer with a £200,000 mortgage and a parent with £50,000 in savings, the effective loan on which interest is charged is reduced by 25% - a meaningful reduction in monthly cost without requiring the parent to give the money away or the buyer to save a larger deposit.
The Benefit to the Family Member
The family member earns no interest on savings held in the linked offset account. Instead, the benefit is delivered as a reduction in the borrower's interest charge. For higher rate taxpayers, this is potentially more tax efficient than earning savings interest, because interest income above the personal savings allowance (£500 for higher rate taxpayers, nil for additional rate taxpayers) is subject to income tax, whereas the offset benefit generates no taxable income.
The family member's savings remain FSCS-protected up to £85,000 per person per authorised institution, in the same way as savings in a standard account - this should be confirmed with the specific lender before proceeding.
Lender Availability
Family offset mortgages are a specialist product and are not widely available across the market. They are offered by a limited number of building societies and specialist lenders. The product may be described as a family offset mortgage, a family savings offset, or a parental savings mortgage depending on the lender. A whole-of-market mortgage broker is the most effective way to identify lenders currently offering this product and to compare terms.
Key Considerations
Before using a family offset mortgage, the following points should be considered:
- The family member's savings are not generating interest - they should assess whether the mortgage interest saving to the borrower is a better return than they could achieve elsewhere after tax.
- The family member should consider what happens if they need to access the savings during the mortgage term - withdrawal reduces the offset benefit immediately and could increase the borrower's monthly payments.
- The mortgage rate on a family offset product may be higher than equivalent non-offset products - the offset benefit must outweigh this rate premium to make the arrangement worthwhile.
- The arrangement should be documented, particularly around any expectation of repayment by the borrower if the family member withdraws the savings.
Frequently Asked Questions
Does the family member need to be a parent or can any family member use a family offset?
This depends on the specific lender's criteria. Most lenders that offer family offset mortgages accept parents and sometimes grandparents as the savings account holder. Some may accept a wider family definition. The lender's eligibility criteria should be checked before applying.
Can the family member withdraw their savings at any time?
Yes. The savings remain the family member's own funds and can be withdrawn at any time, in the same way as funds in a standard savings account. Withdrawal reduces the offset balance and increases the mortgage interest charged from that point. There are no penalties for the family member withdrawing savings, though the impact on the borrower's mortgage costs should be considered.
Is a family offset mortgage the same as a guarantor mortgage?
No. In a guarantor mortgage, the guarantor is legally liable for the mortgage debt if the borrower defaults. In a family offset mortgage, the family member has no liability for the mortgage - their savings are linked to reduce interest charges but they have no obligation to make payments or to keep the savings in place. This makes family offset a significantly lower-risk arrangement for the family member than acting as a guarantor.
What happens to the offset savings when the mortgage is redeemed?
When the mortgage is repaid in full, the link between the savings account and the mortgage is broken and the savings revert to a standard savings account in the family member's name. The family member's funds are not affected by the mortgage being redeemed - they retain their savings in full.
