Mortgage Affordability: How Lenders Assess It and How CeMAP Tests It

Mortgage affordability is the topic CeMAP® comes back to most often. MRT1 AC6.1 names it, AC6.6 adds "methods of verifying information supplied by consumers (plausibility)", and the CeMAP 3 case studies test it again in ASEW AC1.2 ("affordability, suitability and sustainability") and AC4.1. The rules come from MCOB 11.6, introduced by the Mortgage Market Review on 26 April 2014, and they apply across the UK. Income tax in our worked example uses the 2026/27 rates for England, Wales and Northern Ireland; Scotland's bands differ. For the module overview, see the CeMAP 2 (MORT) hub; for the unit, the MRT1 unit guide.

Affordability at a glance	Rule
The duty	MCOB 11.6.2R: assess ability to pay before lending or varying
What counts	MCOB 11.6.5R: net income; committed spending; basic essential and quality-of-living costs
What never counts	Equity in the home, expected price growth, a general declaration of affordability
Evidence	MCOB 11.6.8R: income must be evidenced
Stress test	MCOB 11.6.18R: at least five years, at least +1%, unless fixed for five years or more
Interest-only	MCOB 11.6.41R: a clearly understood, credible repayment strategy

What does mortgage affordability mean in advice?

Affordability in mortgage advice means the customer can meet the mortgage payments now and over the term, from net income after tax, committed spending and essential living costs. MCOB 11.6 makes the assessment the lender's legal duty, and MRT1 AC6.1 tests it.

The adviser has a part to play too. MRT1 LO6 frames affordability as one of seven principles of advice that deliver a fair outcome, alongside suitability, risk and the term. An adviser gathers the income and spending figures, checks they make sense, and should not recommend a mortgage the customer clearly cannot afford. But the decision to lend, and the legal duty to assess affordability, sit with the lender.

ASEW AC1.2 adds a third word: sustainability. A mortgage is sustainable if it stays affordable as circumstances change, through rate rises, children, retirement or a fall in income. The CeMAP 3 case studies often give a future change, such as a planned career break, and ask whether the adviser has accounted for it. That links to MCOB 11.6.14R, which requires the lender to take known or likely future changes in income and spending into account.

The MCOB rules guide puts affordability in the context of the other MCOB chapters.

Key fact: Affordability became the lender's evidenced duty on 26 April 2014, when the Mortgage Market Review ended self-certified lending.

What must a lender check under MCOB 11.6?

MCOB 11.6.2R requires a lender, before entering into or varying a regulated mortgage contract, to assess whether the customer and any guarantor can pay. MCOB 11.6.5R requires net income and, as a minimum, committed, basic essential and basic quality-of-living costs.

The three spending categories have precise meanings in MCOB 11.6.10R:

Category	Meaning	Examples
Committed expenditure	Credit and contractual commitments that continue after completion	Loans, credit cards, hire purchase, child maintenance, the cost of an interest-only repayment strategy
Basic essential expenditure	Household essentials	Food and washing, heating, water, phone, council tax, buildings insurance, ground rent and service charge, essential travel
Basic quality-of-living costs	Hard to reduce and give a basic quality of life	Clothing, household goods, personal goods, basic recreation, childcare

MCOB 11.6.5R also rules three things out. The lender must not base the decision on the equity in the property, must not count on house prices rising, and, under MCOB 11.6.6R, must not rely on a general declaration of affordability from the customer. A lender must assess on a capital-and-interest basis unless the loan is a compliant interest-only mortgage.

When is a full assessment not needed?

MCOB 11.6.3R lets a lender skip a full assessment where an existing customer varies or replaces the mortgage with no extra borrowing (except fees) and no change material to affordability. A like-for-like product switch is the usual case. MCOB 11.6.4E presumes some changes are material: extending the term into retirement, switching between repayment and interest-only, and adding or removing a borrower. Since 22 July 2025, term reductions are also exempt, and under MCOB 11.9 a new lender may use modified affordability on a remortgage with no extra borrowing where the new deal is more affordable.

The full text is in the FCA Handbook, MCOB 11.6.

Exam tip: MCOB 11.6.2R covers the guarantor as well as the borrower. A guarantor who cannot pay does not rescue an unaffordable loan.

How are income and spending verified?

Income is verified because MCOB 11.6.8R requires the lender to obtain evidence of declared income, by documents or automated systems. Spending is checked under MCOB 11.6.12R, which requires reasonable steps to find the customer's actual commitments, often by credit search.

MRT1 AC6.6 calls this "methods of verifying information supplied by consumers (plausibility)". In practice:

1. Employed income. Payslips, a P60 or bank statements showing salary paid in. FCA guidance in MCOB 11.6.13G gives payslips and bank statements as examples.
2. Self-employed income. The rules are the same, but MCOB 11.6.9G says the evidence varies with employment status. Lenders usually ask for HMRC tax calculations and tax year overviews, or accounts, covering more than one year.
3. Variable income. Bonuses, overtime and commission are evidenced over a longer period, and lenders often count only part of them.
4. Commitments. A credit search shows loans and cards; bank statements can reveal others, such as buy-now-pay-later plans or maintenance payments.
5. Living costs. Lenders may use the customer's own figures or statistical data for a household of that size, as long as the result is realistic.

A lender may rely on the evidence it gets unless, taking a common-sense view, it has reason to doubt it (MCOB 11.6.12R). That is the plausibility test. A declared salary of £85,000 for an entry-level job, or bank statements that never show the stated rent being paid, should prompt questions.

Plausibility questions in CeMAP

The adviser's role is to notice when the figures do not fit and to ask, not to adjust them. Practise with the MRT1 advice and affordability drill.

Key fact: Self-certification has gone. Every regulated residential mortgage needs evidenced income under MCOB 11.6.8R.

How does the interest-rate stress test work?

The interest-rate stress test, under MCOB 11.6.18R, makes a lender consider likely rates over at least five years and assume a rise of at least 1%, unless the rate is fixed for five years or more. The customer must still afford that payment.

The rule has three parts:

1. Horizon. At least five years from the start of the mortgage.
2. Basis. The lender must have regard to market expectations, such as the forward rates the Bank of England publishes, and to any Financial Policy Committee recommendation. It must not use its own forecast alone.
3. Floor. Even if markets expect rates to fall, the lender must assume a rise of at least 1% over the first five years.

The exemption for fixes of five years or more explains a pattern candidates notice: a five-year fix often lets a customer borrow more than a two-year fix at the same rate, because the lender may assess it at the fixed rate rather than a stressed one.

The FPC test that was withdrawn

Until 2022 the Bank of England's Financial Policy Committee also required a separate test at 3 percentage points above the lender's reversion rate. The FPC withdrew that test on 1 August 2022, according to the Bank of England announcement, and kept the loan-to-income limit. Older study material that still quotes the 3-point test is out of date.

Exam tip: The stress test is the FCA's rule in MCOB 11.6.18R: five years and at least 1%. The 3-point FPC test ended on 1 August 2022.

What are income multiples and the LTI limit?

An income multiple is a lender's cap on the loan as a multiple of gross income, such as 4.5 times. MCOB 11.6.7G allows it, but a multiple alone never shows affordability. The Bank of England limits loans at 4.5 times income or more to 15%.

Loan to income (LTI) is the loan divided by gross annual income. A £220,000 loan for a couple earning £62,000 between them is about 3.55 times. Lenders often allow higher multiples for higher earners and lower ones where commitments are high, but the multiple is a ceiling, not a test of affordability.

The LTI flow limit is a market-wide rule. No more than 15% of new mortgages, in aggregate, may be at 4.5 times income or more. From 28 October 2026 the limit applies only in aggregate, so an individual lender may lend above 15% at that level while the market stays within it, as set out in the PRA's policy statement. Small lenders below a de minimis level are outside it.

LTI is easy to confuse with loan to value. LTV measures the loan against the property, LTI against income; our loan to value guide compares them side by side.

Key fact: LTI uses gross income. MCOB affordability uses net income, after income tax and National Insurance.

How does an interest-only borrower show a repayment strategy?

An interest-only borrower shows a repayment strategy by giving the lender evidence of a clearly understood, credible plan that can repay the capital, as MCOB 11.6.41R requires. Acceptable plans include regular saving, selling another property, or capital from bonuses; expected house-price growth is not acceptable.

MCOB 11.6.45G lists examples that may be acceptable, depending on the customer:

• regular payments into a savings or investment product;
• periodic capital repayments from irregular income, such as bonuses or some self-employed income;
• the sale of other assets, such as another property or land.

MCOB 11.6.46E lists strategies that tend to show a breach, including relying on the home rising in value enough to repay the loan. Downsizing is possible, but the lender must judge it against the equity and local prices.

Two related rules come up in questions. Under MCOB 11.6.48R, a lender may assess an interest-only loan on interest only, but must then count the cost of the repayment strategy as committed expenditure. And under MCOB 11.6.49R, the lender must review the strategy at least once during the term; lifetime mortgages and retirement interest-only mortgages are exempt from that review. The products are compared on our types of mortgages guide.

Exam tip: "The customer expects the house to be worth more" is never a credible repayment strategy on its own.

What is the difference between affordability and suitability?

Affordability asks whether the customer can pay, and is the lender's duty under MCOB 11.6. Suitability asks whether the mortgage fits the customer's needs and circumstances, and is the adviser's duty under MCOB 4.7A. MRT1 AC6.1 and AC6.2 test them as two separate principles.

	Affordability	Suitability
Question	Can the customer pay?	Is this the right mortgage for them?
Duty holder	Lender	Adviser
Rule	MCOB 11.6	MCOB 4.7A
Based on	Income, spending, stressed rate	Needs, circumstances, preferences, attitude to risk
Can fail when	Payment is too high	Features, rate type, term or costs do not fit

A mortgage can be affordable but unsuitable. A five-year fix with heavy early repayment charges may be affordable for a customer who plans to move abroad in two years, but it is not suitable. The reverse also happens: the most suitable product type may be unaffordable at the size needed, so the adviser must look at a lower loan, a longer term or a different property. A longer term lowers the payment but raises the total interest, and a term into retirement brings MCOB 11.6.15G into play, which asks for more robust evidence of retirement income the closer retirement is.

Key fact: Under MCOB 4.7A an adviser must not recommend the "least worst" product. If nothing suitable is available, the adviser says so.

What is a decision in principle?

A decision in principle (DIP), or agreement in principle, is a lender's indication of how much it might lend, based on basic income details and a credit search. It is not a mortgage offer, binds no one, and MCOB 11.6 does not define it.

A DIP usually comes before a buyer makes an offer on a home, so estate agents and sellers can see the buyer is credible. It lasts for a limited period that the lender sets. It is given before the full affordability assessment, before income is evidenced and before the valuation, so a full application can still be declined or reduced.

Whether a DIP affects a credit file depends on the search. A soft search is visible only to the customer; a hard search is visible to other lenders. In a CeMAP question, the key facts are that a DIP is not binding and does not replace the MCOB 11.6 assessment. The ESIS must still be given before the full application.

Exam tip: The binding document is the mortgage offer, followed by a reflection period of at least 7 days. A decision in principle binds no one.

Worked example: is this mortgage affordable?

This worked example tests a £220,000 repayment mortgage over 25 years for a couple with net income of about £4,307 a month, using the MCOB 11.6.5R categories and the 1% minimum stress. It is affordable, with a margin of about £756.

Amira earns £38,000 and Ben £24,000, both employed in England. They want £220,000 on a two-year fix at 4.5%. Our own illustrative numbers; we ignore pension contributions and student loans to keep the arithmetic clear.

Step 1: net income (2026/27, England)

	Amira	Ben
Gross salary	£38,000	£24,000
Income tax (20% above £12,570)	£5,086	£2,286
National Insurance (8% above £12,570)	£2,034	£914
Net a year	£30,880	£20,800
Net a month	£2,573	£1,733

Combined net income is about £4,307 a month. Rates are on the gov.uk income tax page.

Step 2: spending

1. Committed expenditure: car finance £280 + credit card £70 = £350.
2. Basic essential expenditure: food, energy, water, phone, council tax, buildings insurance and travel = £1,250.
3. Basic quality-of-living costs: clothing, household goods, recreation = £600.
4. Available for the mortgage: £4,307 − £350 − £1,250 − £600 = £2,107.

Step 3: payments and the stress test

1. Payment at 4.5% over 25 years: about £1,223 a month.
2. The fix is only two years, so MCOB 11.6.18R applies. At the 1% minimum rise, test at 5.5%: about £1,351 a month.
3. Margin after the stressed payment: £2,107 − £1,351 = £756.
4. LTI: £220,000 ÷ £62,000 = 3.55 times, below the 4.5 level.

On these figures the loan is affordable. Real lenders use their own stress rates, often higher than the minimum, and their own expenditure models. Two changes would alter the answer. A five-year fix at 4.75% could be assessed at its own rate, about £1,254. If Amira expects to retire in 18 years, the lender must take a prudent view of income beyond that date under MCOB 11.6.15G. The case-study version of this problem is on our CeMAP 3 case studies guide, and more methods are on the CeMAP calculations page.

Key fact: The margin is tested on the stressed payment, not the pay rate. A loan affordable at 4.5% can fail at 5.5%.

Your mortgage affordability study plan

Your mortgage affordability study plan takes about 8 hours over a week: learn the MCOB 11.6 rule numbers and spending categories, redo the worked example with your own figures, then practise 20 scenario questions on MRT1 LO6 and the ASEW solutions topic.

Step	Focus	Practice
1	MCOB 11.6.2R, 11.6.5R, 11.6.18R and 11.6.41R	Write each rule in one line
2	Verification and plausibility	MRT1 advice and affordability drill
3	The worked example with new income and spending	Change the fix length and the term
4	Case-study application	ASEW solutions drill
5	Timed check	Free MRT1 mock 1

Start with the free MRT1 diagnostic, 20 questions in 30 minutes. Buy-to-let lending uses a different test based on rent, the interest cover ratio, explained on our buy-to-let mortgages guide. Our free study notes summarise the rules for quick revision.

Mocks 2 to 10 and the topic drills are part of Pro: £6.99 a week, £11.99 a month or £22.99 for three months, for all five units. Our readiness rule is three mocks in a row at 85% or more, with every topic at 80% or more. It is a guide, and there is no pass guarantee.