Last reviewed: June 2026
TL;DR- The loan-to-income (LTI) ratio is the mortgage amount divided by the borrower's gross annual income - a key determinant of the maximum loan available.
- Most lenders cap LTI at 4-4.5 times income for standard residential mortgages.
- The Bank of England's Financial Policy Committee limits new lending above 4.5x LTI to 15% of total new mortgage lending - this constrains high-multiple lending across the market.
- Some lenders offer higher multiples (up to 5-5.5x) for specific professional groups or high-income borrowers, within their FPC flow limit headroom.
How LTI Is Calculated
Loan to income = mortgage amount / gross annual income. A £180,000 mortgage for a borrower earning £40,000 per year = LTI of 4.5. For joint applications, LTI is typically calculated on combined gross income: a couple earning £30,000 and £25,000 respectively (combined £55,000) borrowing £220,000 = LTI of 4.0. Some lenders apply different income multiples for sole vs joint applications.
LTI is the starting point for maximum loan calculation but the actual maximum offered may be lower after the affordability assessment - factoring in expenditure, existing commitments and the stress test. A borrower may pass the LTI test but fail the expenditure-adjusted affordability test, resulting in a lower actual offer.
The FPC Flow Limit
The Bank of England's Financial Policy Committee imposes a flow limit on LTI lending: no more than 15% of the total value of new regulated residential mortgage lending in any given quarter may be at an LTI ratio above 4.5. This limit applies at the lender level - each lender manages its own 15% headroom. The limit prevents any individual lender from systematically lending at high income multiples while providing flexibility for a minority of transactions (typically higher-income borrowers with strong financial profiles) to exceed 4.5x.
In practice, lenders manage this headroom carefully. Periods of high demand at high LTI ratios may see lenders temporarily tighten their criteria above 4.5x LTI if their headroom is near exhaustion. Conversely, lenders with unused headroom may be more willing to consider higher-multiple applications.
Professional Mortgages and Higher Multiples
Some lenders offer higher income multiples for specific professional groups - doctors, dentists, solicitors, accountants and similar professions with strong career progression and income certainty. These professional mortgage products may offer up to 5 or 5.5 times income, within the lender's available FPC headroom. Professional mortgage eligibility is defined by the lender and varies - it is typically restricted to qualifying professions and minimum income levels.
LTI vs Affordability
LTI is a blunt measure - it compares loan to income without considering outgoings. Affordability is the more nuanced assessment that considers income net of tax and expenditure. The FCA requires affordability (net income after expenditure) rather than LTI to be the primary basis for the lending decision. In practice, LTI acts as an upper limit: the actual loan may be lower than the LTI multiple would allow once expenditure and stress testing are applied.
Frequently Asked Questions
Can I borrow more than 4.5 times my income?
Some lenders do offer above 4.5x for specific borrower profiles and professional groups, within their FPC headroom. Above 4.5x is not available from all lenders and may not be available from any lender at certain times when headroom is exhausted. A whole-of-market broker can identify which lenders currently have headroom for above-4.5x lending and which borrower profiles they target.
Is the LTI limit the same for all mortgage types?
The FPC's 15% flow limit applies to regulated residential mortgages. It does not apply directly to buy-to-let mortgages (which are assessed on rental income coverage rather than personal income multiple), commercial mortgages or unregulated lending. The LTI flow limit is specifically a residential mortgage macroprudential tool.
Does a joint application improve LTI?
Yes. Combined income in a joint application increases the assessable income and therefore the maximum LTI-based loan. A couple with combined income of £80,000 can access a maximum loan of £360,000 at 4.5x LTI. If only one partner earns £50,000, the sole maximum would be £225,000 at 4.5x. The joint application effectively pools income for LTI purposes. Both borrowers' outgoings and credit histories are also assessed jointly.
What counts as income for LTI purposes?
The income used in LTI calculations is the gross assessable income as defined by the lender. For employed borrowers this is typically basic salary; bonuses, overtime and commission may be included at a percentage depending on the lender. For self-employed borrowers it is net profit or salary plus dividends. Benefits income, rental income and investment income may or may not be included depending on the lender's specific criteria. The definition of assessable income therefore varies between lenders, which is one reason the same borrower can access different maximum loans from different lenders.
