How to read a mortgage illustration (ESIS / KFI)

When a broker or lender quotes a remortgage or product transfer, they must give you a standardised illustration. You may see it labelled a European Standardised Information Sheet (ESIS), a Key Facts Illustration (KFI), or simply a mortgage illustration. The names differ with product rules and timing; the job is the same: put rate, fees, payments, early repayment charges and follow-on assumptions in one place so you can compare deals section by section.

This guide does not invent a sample lender illustration, fake APRC, or made-up monthly payment. Open the document you were given. Match each field below to the line on your pages, then type those figures into the Remortgage Lab calculators. The calculators are illustrative tools for organising numbers — not advice, not an offer, and not a substitute for the illustration or the formal mortgage offer that follows.

What the document is (and is not)

An illustration is a regulated pre-contract summary. MoneyHelper notes that advisers must give you a mortgage illustration covering repayments, upfront fees, overall cost, interest type and APRC, what happens if rates rise, special features such as overpaying, and what happens if you no longer want the mortgage. The Financial Conduct Authority (FCA) sets content rules so illustrations follow a consistent layout. That consistency is why you can compare two quotes field by field instead of hunting through marketing PDFs.

It is not the final mortgage offer. Figures can change if the valuation, loan size, completion date or underwriting outcome moves. It is also not a recommendation on its own — a suitability report (when advice is given) sits beside it. Treat the illustration as the input sheet for your own arithmetic, then re-check every line when the formal offer arrives.

Before you start — have the right papers open

• The illustration for the product you are seriously considering
• Your current mortgage offer or statement (balance, deal end date, ERC wording) if you are remortgaging or transferring
• Any retention or product-transfer quote from your existing lender, if one has been issued

If paperwork is still scattered, the remortgage documents checklist lists what to gather. Fee types and indicative UK ranges are covered separately in Remortgage fees explained.

Loan amount, term and repayment type → repayment calculator

Near the front of an ESIS or illustration you will find the main features of the loan: property (or security), loan amount, currency, term, and whether the mortgage is repayment, interest-only, or a mix. Copy the loan amount and remaining term exactly as shown for the scenario you want to model. If the illustration assumes fees are added to the advance, note the higher loan figure — that is the balance the payment is calculated on.

Enter those values, with the initial product rate, in the Mortgage repayment calculator. Use it to sanity-check the instalment on the illustration, not to replace it. If your figure and the document diverge, check day-count assumptions, whether insurance or other add-ons are bundled into the quoted payment, and whether you typed the fee-inclusive loan.

Interest rate, follow-on rate and APRC → true cost (and SVR awareness)

Illustrations spell out the initial rate (fixed, tracker or discount), how long it lasts, and what follows — often a reversion to a standard variable rate (SVR) or another named follow-on rate. They also show an APRC (Annual Percentage Rate of Charge): a standardised annual cost measure that folds in interest and certain charges so products can be compared on a like-for-like basis. APRC is useful for orientation; it is not the same as “what I pay for the next two years of this fix.”

For remortgage decisions over a chosen horizon (for example 24 months), map:

• Initial rate → the “new deal” rate input on the Remortgage true cost calculator
• Current deal rate (from your existing offer/statement) → the “stay / current” side of the same comparison
• Follow-on / SVR → a separate scenario if your illustration or current paperwork shows what happens after the product ends and you have not booked a new deal

Do not invent an SVR. Only use a figure written on your lender materials. If the illustration shows a rate-rise example in a risk section, treat that as a stress test, not as a forecast.

Fees and cashback → true cost + remortgage fees guide

Fee lines usually appear as one-off costs, costs added to the loan, or costs paid regularly. Common remortgage items include product / booking / arrangement fees, valuation, legal or conveyancing packages, broker fees, exit or discharge fees on the old loan, and (rarely) a higher lending charge. Cashback, if any, is typically shown with conditions and clawback.

For each sterling amount on your illustration:

1. Write whether it is paid upfront or added to the loan.
2. Enter the amount in the matching fee field on the Remortgage true cost calculator.
3. Cross-check the fee type against Remortgage fees explained if the label is unfamiliar — ranges there are indicative only; your illustration wins.

A lower headline rate with a four-figure product fee can lose to a slightly higher fee-free rate over a short fix. Putting every fee line into the true-cost sheet is how you see that without relying on marketing labels.

Early repayment charges → ERC calculator

Look for the section on leaving early or early repayment charges (ERCs). Your current deal’s ERC (if still in force) is often the deciding cost of switching lenders before the deal end date. The new illustration’s ERC schedule matters if you might leave that product early later.

Note the method: percentage of balance, sliding scale by year, months of interest, or a fixed sum — and the date the charge ends. Then use the Early repayment charge calculator with the balance and percentage (or other method) from your offer wording. Fold any confirmed ERC into the true-cost comparison as a cost of leaving. For how percentage-of-balance and months-of-interest maths differ, see How ERCs are calculated. Never guess an ERC percentage that is not on your paperwork.

Monthly instalments and payment timetable → repayment check

Illustrations show payment frequency and the amount of each instalment during the initial rate period, and often a different amount after reversion. Confirm which box is the deal payment and which is the follow-on example. Re-run the repayment calculator with the follow-on rate only if that rate is stated on your document and you want a “what if nothing is booked” sketch — still labelled as illustrative on your side.

Overpayment allowances, underpayment or payment-holiday features, and portability sit in features or “what happens if…” sections. They rarely change the first true-cost pass, but they affect flexibility. Note any overpayment limit before ERC if you plan to pay down faster; the Overpayment calculator can model extra payments once those limits are clear from your wording.

Quick mapping table

• Loan amount + term + initial rate → Mortgage repayment
• Initial rate + fees + cashback + horizon → Remortgage true cost
• Fee line labels / what they mean → Remortgage fees
• ERC % or method + balance → Early repayment charge
• Current vs new-lender vs transfer quotes → Remortgage vs product transfer once each side’s rate and fees are taken from real illustrations

Worked method (your figures only)

A safe sequence that stays tied to documents you hold:

1. From the illustration: copy loan, term, initial rate, each fee, cashback, and the ERC schedule for the new product.
2. From the current mortgage: copy balance, current rate, months left, ERC method and any exit fee.
3. Run repayment once to confirm the instalment on the illustration is understood.
4. Run true cost over the same horizon for stay / transfer / new-lender paths, using only written rates and fees.
5. If an ERC still applies on the old deal, run the ERC calculator and add that sterling result as a switching cost.
6. When the formal offer arrives, re-check every line — do not assume the illustration and the offer are identical.

Remortgage Lab’s shared EXAMPLE house figures appear elsewhere on the site for teaching the maths. They are not a substitute for your illustration and are not used on this page as a fake lender quote.

Common pitfalls

• Comparing APRC alone while ignoring a large ERC still live on the current deal
• Ignoring “fees added to the loan” and understating the balance that interest runs on
• Treating a free valuation or free legal pack as universal — eligibility rules often apply
• Mixing a product-transfer illustration with a new-lender illustration without aligning horizons and fee stacks
• Assuming the follow-on rate example is what you will pay if you plan to remortgage again before reversion — your next product will need its own illustration

Sources and further reading

We write in our own words. For independent consumer guidance on what a mortgage illustration must cover when you take advice, see MoneyHelper on choosing a mortgage and the illustration document. For the FCA’s consumer-facing mortgages information, see the FCA consumer mortgages pages. Those sources explain process and protections. They are not a substitute for reading the illustration and offer issued for your case.

Disclaimer

This guide is illustrative only. It is not personalised financial advice. It is not a credit or mortgage offer. It is not an FCA-regulated recommendation. Illustration layouts and labels vary by firm and product. Always use the figures on your own ESIS, Key Facts Illustration or mortgage illustration and on your formal offer. If you want advice on your situation, speak to an FCA-authorised mortgage adviser.

Next steps

Open your illustration, then enter rate, fees and horizon in the Remortgage true cost calculator. Use Remortgage fees explained if a fee label is unclear, and the ERC and repayment calculators for the matching lines. This site helps you map the document to the arithmetic; it does not tell you which deal to take.