Offset mortgage vs standard mortgage — how do they compare?
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In short. An offset mortgage links a savings account to your mortgage and only charges interest on the difference. A standard mortgage charges interest on the full loan balance regardless of any savings you hold elsewhere.
Offset mortgages can be a tax-efficient way to use savings without losing access — your savings 'work' against the mortgage instead of earning taxable interest. They typically come with a slightly higher headline rate, so the maths depends on how much you save.
Last reviewed:
Side by side
Interest calculation
Offset mortgage
On (mortgage balance − linked savings)
Standard mortgage
On full mortgage balance
Savings access
Offset mortgage
Yes — savings remain available
Standard mortgage
N/A (savings held separately)
Interest on savings
Offset mortgage
None — they reduce mortgage interest instead
Standard mortgage
Earned and taxed via PSA / ISA
Headline mortgage rate
Offset mortgage
Usually slightly higher than equivalent non-offset
Standard mortgage
Standard market rate
Tax efficiency
Offset mortgage
Effectively gross-rate equivalent — no tax on interest 'saved'
Standard mortgage
Savings interest may be taxed above the PSA
Typical use
Offset mortgage
Higher-rate taxpayers with sizeable savings; self-employed with reserve cash
Standard mortgage
Standard residential and BTL borrowing
When Offset mortgage usually wins
- You hold meaningful savings and want them to reduce mortgage interest
- You're a higher- or additional-rate taxpayer above your PSA
- You want flexible access to savings without forfeiting the benefit
- You're self-employed and keep a tax reserve
When Standard mortgage usually wins
- You have little in savings to offset
- You want the lowest possible headline mortgage rate
- Your savings sit in a tax wrapper (ISA / pension) already
- You don't need to combine savings and mortgage in one provider
Related quick answers
FAQ
- Do my offset savings reduce monthly payments or shorten the term?
- Most offset products give you the choice: keep payments the same and shorten the term, or lower the monthly payment with the original term.
- Are offset savings FSCS-protected?
- Yes — the linked savings account is normally an ordinary deposit covered by FSCS up to £85,000 per banking licence.
- Is the maths worth it?
- It depends on your tax band and the rate gap. As a rule of thumb, the more of your mortgage you can offset, the better — and the higher your tax rate, the more valuable the tax-free benefit.