UK Interest-Only Mortgages Explained

An interest-only mortgage pays only the interest each month, with the full original capital due in a single lump sum at the end of the term. The structure is less common than full repayment for owner-occupier mortgages but still available, subject to stricter lender criteria than after the 2014 Mortgage Market Review.

How interest-only works

Monthly payments cover only the interest accruing on the loan. The capital balance remains constant throughout the term unless the borrower makes additional overpayments. At term end, the full original capital is due in a single repayment, typically funded by a designated repayment vehicle.

The repayment vehicle requirement

Under FCA rules, lenders must check that the borrower has a credible plan to repay the capital. Common acceptable vehicles include investment portfolios, ISAs, pension tax-free cash, and sale of a separate investment property. Sale of the mortgaged property is rarely accepted as the sole plan because it leaves the borrower without a home.

Part-and-part structures

Part-and-part mortgages split the loan into an interest-only portion and a repayment portion. The interest-only portion keeps monthly payments lower; the repayment portion ensures that at least some capital is paid down over the term. Lenders may accept less stringent repayment vehicle evidence for part-and-part than for pure interest-only.

Typical eligibility

Interest-only mortgages typically require higher income, larger deposits, and stronger evidence of the repayment vehicle than repayment mortgages at the same LTV. Eligibility criteria vary widely by lender; some specialise in interest-only and some have exited the market.

Why the market has changed

Interest-only mortgages were widely available in the UK in the 1980s, 1990s, and early 2000s without lender verification of the repayment plan. Many borrowers chose interest-only for the lower monthly payment, often with the unstated intention of selling the property or relying on future income to repay the capital. After the 2008 financial crisis and the 2014 Mortgage Market Review, the FCA tightened rules requiring lenders to verify a credible repayment vehicle.

This shift has produced a wave of borrowers approaching the end of their interest-only term without an evidenced repayment plan. The FCA's interest-only mortgages review and ongoing supervisory work has focused on lender treatment of these borrowers and on options including term extension, switch to repayment, or sale of the property.

New interest-only mortgages are still available but the underwriting is much stricter than historically. Typical requirements include higher deposits (often 25% or 50% LTV maximum), stronger evidenced income, and verified repayment vehicle with quantified projected value.

Acceptable repayment vehicles in detail

Investment portfolios (such as ISAs, pension lump sums, or general investment accounts) are the most common evidenced repayment vehicles. Lenders typically require evidence of current value, projected value at maturity using prudent growth assumptions, and the borrower's understanding of the investment risk. ISA and pension projections at conservative growth rates may produce a projected balance well below the mortgage capital, requiring either higher contributions or a smaller interest-only portion.

Sale of an investment property is accepted by some lenders, particularly where the borrower owns multiple properties. The borrower's primary residence cannot typically be the repayment vehicle because it leaves the borrower without a home. The investment property's value, mortgage status, and likely sale proceeds need to be evidenced.

Tax-free pension lump sums (up to 25% of pension value, now subject to the Lump Sum Allowance after the LTA abolition in April 2024) can be accepted as repayment vehicles. The pension balance must be evidenced and the projected lump sum at access age estimated under prudent assumptions. Lenders typically discount the headline pension projection to account for the contribution-and-growth uncertainty.

Inheritance is generally not an acceptable repayment vehicle because it is not under the borrower's control. Some lenders may accept named inheritance with appropriate evidence (such as a will and the testator's confirmation) but this is rare and case-by-case.

Part-and-part structures

Part-and-part mortgages split the loan into an interest-only portion and a repayment portion. The interest-only portion keeps monthly payments lower than full repayment; the repayment portion ensures that at least some capital is paid down over the term. Common splits include 50/50, 75/25 (repayment/interest-only), and other ratios depending on lender criteria and borrower preference.

Lenders may accept less stringent repayment vehicle evidence for part-and-part than for pure interest-only because the interest-only portion is smaller. The repayment vehicle requirement still applies but the absolute value needed is lower. This makes part-and-part a practical compromise for borrowers who want some monthly payment reduction without committing to fully verified interest-only.

Part-and-part can also be structured to allow the interest-only portion to be converted to repayment over time. As the borrower's income grows, additional capital repayment becomes affordable, and the interest-only portion shrinks. Lenders' processes for this conversion vary; some allow ongoing adjustment, others require formal product transfer.

Approaching term end on an existing interest-only mortgage

Borrowers approaching the end of an interest-only term should engage with their lender at least 12 to 24 months before the term end. The lender's options typically include: term extension (with affordability reassessment), switch to repayment (with the monthly payment increasing significantly), product transfer to a new deal, sale of the property and repayment, or specialist routes such as RIO or equity release.

Term extension may be granted under the Mortgage Charter forbearance provisions or via standard affordability assessment. For older borrowers approaching retirement, lender willingness to extend depends on income evidence in retirement (such as pension projections). The 'maximum age at term end' set by each lender determines the upper bound.

Switching to repayment dramatically increases the monthly payment because the entire capital now needs to be paid down over the remaining term. The increase can be unaffordable if the borrower is no longer working at full income. Switching to part-and-part is sometimes a middle ground.

Retirement Interest-Only (RIO) mortgages are designed for older borrowers (typically 55+) who want to remain on interest-only into retirement. The mortgage is repaid on sale of the property, death, or move into long-term care. RIO requires affordability against the interest-only payment from pension income.

RIO and equity release alternatives

Retirement Interest-Only (RIO) mortgages provide an interest-only structure with no defined term end; the loan is repaid on sale, death, or move into care. RIO is typically affordability-assessed against retirement income such as pension drawdown. Specialist lenders (such as Hodge Bank, Marsden Building Society) dominate this market.

Equity release schemes (lifetime mortgages and home reversion) are different products. A lifetime mortgage charges interest that typically rolls up rather than being paid monthly, with the loan repaid on death or move into care. Equity release is regulated by the FCA and the Equity Release Council provides additional protections (such as the no-negative-equity guarantee). Equity release has historically attracted concern about high effective interest rates and erosion of inheritance; modern products with the ERC standards address some of these concerns.

FCA regulatory framework and post-MMR rules

Interest-only mortgages are regulated by the FCA under MCOB (Mortgages and Home Finance: Conduct of Business). The 2014 Mortgage Market Review (MMR) introduced specific rules tightening interest-only sales after concerns about borrowers reaching term end without a credible repayment plan. MCOB 11.6 requires lenders to assess affordability and verify a credible repayment vehicle at application.

For new interest-only mortgages, the lender must obtain evidence of the repayment vehicle and form a reasonable view that it will produce sufficient funds to repay the capital at term end. The Home Office's guidance and the FCA's responsible lending sourcebook (CONC for consumer credit, MCOB for mortgages) set out the standards.

For existing interest-only mortgages taken out before MMR, lenders' obligations focus on customer outcomes at maturity rather than retrospective re-underwriting. The FCA has reviewed lenders' interest-only books periodically; the Interest-Only Mortgages Review identified the cohort of borrowers approaching term end without clear repayment plans.

Worked example: a borrower with a GBP 200,000 interest-only mortgage at 5% pays monthly interest of around GBP 833 (GBP 200,000 x 5% / 12). Over a 25-year term, the total interest paid is approximately GBP 250,000, with the original GBP 200,000 capital due at term end via the repayment vehicle. Comparison with a 25-year repayment mortgage at 5%: monthly payment around GBP 1,169, total paid GBP 350,750, with no separate capital due at term end.

The practical takeaway: interest-only suits borrowers with substantial assets or income who can fund a credible repayment vehicle; it does not suit borrowers relying on hope or expected future income. The FCA framework protects against the worst sales practices but the borrower retains responsibility for the capital at term end.

Term-end transitions and the Mortgage Charter forbearance options

For borrowers approaching the end of an interest-only term, the Mortgage Charter (the June 2023 voluntary agreement between major lenders and HM Treasury) provides specific forbearance options. The Charter commitments include the ability to switch temporarily to interest-only for 6 months without affordability reassessment, and the ability to extend the term for up to 6 months.

These Charter options provide breathing space rather than long-term solutions. For longer-term restructuring (such as permanent term extension, switch from interest-only to repayment, or part-and-part conversion), the standard affordability assessment applies; the lender's underwriting determines feasibility.

For older borrowers (typically 55+) facing interest-only term end with insufficient repayment vehicle, retirement interest-only (RIO) mortgages provide an alternative. RIO mortgages run for the borrower's lifetime with the loan repaid on death, move into long-term care, or sale of the property. RIO eligibility is typically affordability-assessed against retirement income.

Equity release (lifetime mortgages and home reversion plans) is another route for older borrowers. Equity release is regulated by the FCA and additionally by the Equity Release Council standards (which include the no-negative-equity guarantee). The relative cost of equity release vs RIO depends on the specific products and the borrower's circumstances; specialist regulated advice is essential.

The practical takeaway: engage with the lender 12 to 24 months before term end to discuss options; explore Charter forbearance, refinancing, and specialist later-life products; consider regulated advice for complex situations.

Retirement Interest-Only (RIO) mortgages for older borrowers

For older borrowers (typically 55+) facing interest-only term end with insufficient repayment vehicle, retirement interest-only (RIO) mortgages provide an alternative. RIO mortgages run for the borrower's lifetime; the loan is repaid on death, move into long-term care, or sale of the property.

RIO eligibility is typically affordability-assessed against retirement income (such as pension drawdown, State Pension, annuity income). Specialist lenders (such as Hodge Bank, Marsden Building Society, LiveMore) dominate the RIO market; mainstream lenders typically do not offer RIO.

For applicants with interest-only mortgages reaching term end and insufficient repayment vehicle, RIO can preserve the home without forced sale. The trade-off is that the mortgage continues into retirement; the home is eventually sold to repay the loan.

Equity release as an alternative for older borrowers

For older borrowers (typically 55+) interest-only mortgages reaching term end, equity release (lifetime mortgages) provides an alternative. Lifetime mortgages charge interest that typically rolls up; the loan is repaid on death or move into care. The Equity Release Council standards (including the no-negative-equity guarantee) provide consumer protections. Specialist regulated advice is essential.

Disclaimer

This article provides general information based on rules and figures published by UK government and regulator sources as of May 2026. It is not personal financial, legal, immigration or tax advice. Rules, fees and figures change and individual circumstances vary. Readers should check primary sources or consult a qualified, regulated adviser before acting on any information here.

Frequently asked questions

Can the repayment vehicle change during the term?

Yes, but the lender may require evidence of the alternative vehicle and may review affordability at switch points. Common changes include moving from one investment vehicle to another (such as ISA to pension), increasing the contribution rate, or adding a second vehicle. The change should be documented and the lender notified; some lenders require formal re-evidencing at periodic review points (often every 5 years).

Is interest-only cheaper monthly than repayment?

Yes, because the monthly payment includes no capital. On a GBP 250,000 mortgage at 5%, interest-only monthly payment is around GBP 1,042 (interest only); repayment monthly payment over 25 years is around GBP 1,461. The interest-only saving is around GBP 420 per month. Total interest paid over the term is typically higher on interest-only because the capital never reduces; the same loan over 25 years pays around GBP 312,000 in interest on interest-only vs around GBP 188,000 on repayment.

Are interest-only buy-to-let mortgages the same?

No. Buy-to-let mortgages have separate rules and are typically not regulated by the FCA in the same way as residential mortgages (unless they meet the consumer buy-to-let criteria). Interest-only is much more common on buy-to-let because the landlord's intention is typically to repay through eventual property sale and the rental income covers the interest. The 2017 to 2020 reforms to mortgage interest deductibility against rental income affected the economics of buy-to-let interest-only structures.

What happens if the repayment vehicle underperforms?

The borrower remains liable for the full capital at term end. Lenders typically request progress updates at periodic reviews (often every 5 years) and may offer term extension or product change if the projection falls short. The earlier the shortfall is identified, the more options exist (such as increasing contributions, switching to part-and-part, or arranging a planned sale). Leaving the shortfall to be addressed at term end can force a hurried sale of the property.

Can an existing repayment mortgage be switched to interest-only?

Sometimes, subject to fresh underwriting and repayment vehicle evidence. The lender's policy and the borrower's circumstances determine eligibility. The switch can reduce monthly payment significantly, which may help in temporary cash flow difficulty, but the capital must then be repaid via the evidenced vehicle. The Mortgage Charter allows a 6-month switch to interest-only without affordability reassessment, providing short-term flexibility without long-term commitment.

What if a borrower's interest-only mortgage from the 1990s reaches term end without a repayment plan?

Options include selling the property and downsizing, switching to a RIO if eligible, equity release if suitable, term extension by the existing lender, or moving to a new mortgage with another lender that accepts the case. Engaging with the lender 12 to 24 months before term end provides the most options. The Mortgage Charter forbearance provisions also apply if the borrower is facing difficulty.

Are interest-only mortgages a bad idea?

Not inherently; they can be appropriate for borrowers with a clear evidenced repayment vehicle, such as those with substantial investment portfolios or pension provisions. The risk historically has been borrowers taking interest-only without a credible repayment plan and reaching term end unable to repay. Modern FCA rules require evidenced repayment vehicle at application, reducing this risk for new mortgages.

Frequently asked questions

Can the repayment vehicle change during the term?

Yes, but the lender may require evidence of the alternative vehicle and may review affordability at switch points. Common changes include moving from one investment vehicle to another (such as ISA to pension), increasing the contribution rate, or adding a second vehicle. The change should be documented and the lender notified; some lenders require formal re-evidencing at periodic review points (often every 5 years).

Is interest-only cheaper monthly than repayment?

Yes, because the monthly payment includes no capital. On a GBP 250,000 mortgage at 5%, interest-only monthly payment is around GBP 1,042 (interest only); repayment monthly payment over 25 years is around GBP 1,461. The interest-only saving is around GBP 420 per month. Total interest paid over the term is typically higher on interest-only because the capital never reduces; the same loan over 25 years pays around GBP 312,000 in interest on interest-only vs around GBP 188,000 on repayment.

Are interest-only buy-to-let mortgages the same?

No. Buy-to-let mortgages have separate rules and are typically not regulated by the FCA in the same way as residential mortgages (unless they meet the consumer buy-to-let criteria). Interest-only is much more common on buy-to-let because the landlord's intention is typically to repay through eventual property sale and the rental income covers the interest. The 2017 to 2020 reforms to mortgage interest deductibility against rental income affected the economics of buy-to-let interest-only structures.

What happens if the repayment vehicle underperforms?

The borrower remains liable for the full capital at term end. Lenders typically request progress updates at periodic reviews (often every 5 years) and may offer term extension or product change if the projection falls short. The earlier the shortfall is identified, the more options exist (such as increasing contributions, switching to part-and-part, or arranging a planned sale). Leaving the shortfall to be addressed at term end can force a hurried sale of the property.

Can an existing repayment mortgage be switched to interest-only?

Sometimes, subject to fresh underwriting and repayment vehicle evidence. The lender's policy and the borrower's circumstances determine eligibility. The switch can reduce monthly payment significantly, which may help in temporary cash flow difficulty, but the capital must then be repaid via the evidenced vehicle. The Mortgage Charter allows a 6-month switch to interest-only without affordability reassessment, providing short-term flexibility without long-term commitment.

What if a borrower's interest-only mortgage from the 1990s reaches term end without a repayment plan?

Options include selling the property and downsizing, switching to a RIO if eligible, equity release if suitable, term extension by the existing lender, or moving to a new mortgage with another lender that accepts the case. Engaging with the lender 12 to 24 months before term end provides the most options. The Mortgage Charter forbearance provisions also apply if the borrower is facing difficulty.

Are interest-only mortgages a bad idea?

Not inherently; they can be appropriate for borrowers with a clear evidenced repayment vehicle, such as those with substantial investment portfolios or pension provisions. The risk historically has been borrowers taking interest-only without a credible repayment plan and reaching term end unable to repay. Modern FCA rules require evidenced repayment vehicle at application, reducing this risk for new mortgages.