A mortgage is the largest financial commitment most people will ever make, yet it's often approached with less preparation than a holiday booking. This guide walks through the entire mortgage journey in order — how mortgages work, the decisions about rate type and term, what lenders actually assess, the application process itself, and what happens for years afterwards through remortgaging and overpayments. Several topics here have their own dedicated deep-dive elsewhere on Poqet — where that's the case, this guide gives you the orientation and links to the detail, rather than repeating it.
1. How mortgages work
A mortgage is a loan secured against the property you're buying, repaid over an agreed term — typically 25 to 35 years — with the lender holding a legal charge over the property until the debt is cleared. Four numbers define almost every mortgage: the loan amount (the amount borrowed), the deposit (the difference between the loan and the purchase price, expressed as a percentage), the interest rate, and the term (how many years you have to repay it).
Loan-to-Value (LTV) — the loan amount as a percentage of the property's value — is the single number that most influences which rates you'll be offered. Lenders price risk in LTV bands: a borrower at 60% LTV is offered meaningfully better rates than one at 90% LTV, because the lender's exposure if prices fall and the property needs repossessing is proportionally smaller. This is why even a modest increase in deposit size — enough to cross from one LTV band into the next — can unlock a noticeably better rate, sometimes saving more in reduced interest than the extra deposit itself cost to save.
Two terms you'll encounter throughout this guide are worth defining precisely now. An Early Repayment Charge (ERC) is a penalty, usually a percentage of the outstanding balance, charged if you repay some or all of a fixed or discounted deal before its term ends — it exists because the lender has effectively priced in you staying for the full fixed period, and exiting early disrupts that. ERCs typically reduce in stages over the deal (for example, 5% in year one of a 5-year fix, falling to 1% in year five). Porting is the ability to move your existing mortgage deal to a new property if you move home during the fixed period, avoiding the ERC — not every mortgage is portable, and porting still requires fresh affordability assessment on the new property, but it's worth checking if you think you might move before your current deal ends.
Most new buyers fixate on the headline interest rate, but the number that determines your monthly payment and total interest is the combination of rate, loan amount, and term together. A slightly higher rate on a shorter term can cost less in total interest than a lower rate stretched over a longer one — always compare using the actual monthly payment and total cost figures, not the rate in isolation. The mortgage calculator does this calculation instantly for any combination.
2. Repayment vs interest-only
A repayment mortgage pays down both interest and capital every month, guaranteeing the loan is fully cleared by the end of the term — this is the default and by far the most common structure for residential mortgages in the UK. An interest-only mortgage has a lower monthly payment because you're only covering the interest charge, but the full capital balance remains outstanding throughout the term and must be repaid in full at the end, typically through a separate investment vehicle, savings plan, or sale of the property.
Interest-only is far more common in buy-to-let, where the capital is often expected to be repaid eventually through sale or refinancing rather than gradual amortisation, and where landlords frequently prefer the lower monthly outgoing to maximise cashflow. For a residential mortgage on your own home, interest-only requires lenders to see a credible, evidenced repayment strategy at application — simply hoping the property will have appreciated enough by the end of the term is not accepted as a repayment vehicle by mainstream lenders.
Model both structures for your own numbers using the interest-only mortgage calculator.
3. Fixed, tracker, and other rate types
The rate type determines how your payment behaves over time, independent of the repayment structure above.
Locked for a set period (commonly 2, 5, or 10 years). Protects against rate rises during the fixed period, but you won't benefit if rates fall, and an Early Repayment Charge usually applies if you leave before the term ends.
Moves directly with the Bank of England base rate plus a set margin. Payments rise and fall with the base rate — cheaper when rates are falling, more expensive when they're rising.
A set discount below the lender's Standard Variable Rate for a fixed period. Less common than fixed or tracker deals, and still moves if the lender's SVR changes.
The rate every deal reverts to once its fixed or discount period ends, unless you remortgage. Currently running 7.5–8.5% against best fixes around 4.1–4.5% — almost always worth avoiding through timely remortgaging.
Most UK borrowers choose a fixed rate for the certainty it provides on monthly budgeting, particularly first-time buyers stretching to the edge of affordability. Compare the fixed vs variable trade-off for your specific numbers using the fixed vs variable calculator.
4. Deposits
The minimum deposit for most residential mortgages is 5% of the purchase price, though the rate offered at 95% LTV is meaningfully higher than at 90%, 85%, 80%, or 75% — each threshold typically unlocking a better rate tier. On the current average UK house price of around £292,000, a 5% deposit is roughly £14,600, while a 25% deposit (a common threshold for the best rates) is closer to £73,000.
| Deposit | LTV | Typical rate tier (5yr fix, 2026) |
|---|---|---|
| 5% | 95% | Highest tier — typically 5.0–5.6% |
| 10% | 90% | 4.6–5.1% |
| 15% | 85% | 4.3–4.7% |
| 25%+ | 75% or below | Best available — typically 4.1–4.4% |
For the full breakdown of exactly how much you need and the realistic timeline to save it, see How Much Deposit Do I Need? and How to Save for a House Deposit.
5. Credit scores
Lenders use credit reference agency data alongside their own internal scoring to assess risk, and the bar for mortgage lending is generally higher than for everyday credit products like a credit card. There's no single universal "mortgage credit score" — different lenders weight different factors, which is partly why being declined by one lender doesn't mean every lender will decline you, and why a mortgage broker with knowledge of individual lenders' criteria can be genuinely valuable for borrowers with anything other than a clean, simple credit history.
The factors that matter most are consistency and recency: a missed payment from six years ago carries far less weight than one from six months ago, and lenders generally want to see at least the most recent 3–6 months of bank statements showing stable, explainable financial behaviour rather than large unexplained transactions. For the full detail on what lenders look for and how to improve your position before applying, see What Credit Score Do You Need for a Mortgage?
6. Affordability
Mortgage affordability in the UK is assessed primarily through income multiples and stress testing, not a simple fixed ratio. Most lenders will lend up to around 4.5–5 times gross annual income, though this varies by lender and by your specific financial circumstances — existing debt, dependants, and outgoings all reduce the multiple a lender is willing to offer in practice, even if the headline multiple suggests more.
Stress testing is the less visible part of the assessment: lenders check whether you could still afford the mortgage at a notably higher interest rate than you're actually being offered, to ensure affordability holds up if rates rise during the term. This is why two borrowers with identical income and deposit can be offered different maximum loan amounts — their existing financial commitments change how much headroom the stress test leaves.
Take a borrower earning £45,000 with no significant existing debt. At a 4.5× income multiple, the headline maximum loan is £202,500. But if the lender stress-tests at 7.5% (well above the actual 4.3% rate being offered) and that stressed monthly payment would exceed a set proportion of take-home pay, the lender may cap the actual offer below the income-multiple maximum — commonly to something closer to £185,000–£195,000 in practice. A second borrower with the same income but an existing £400/month car finance commitment would likely be offered less again, since that committed outgoing reduces the income available to absorb the stressed payment. This is precisely why an Agreement in Principle, discussed next, is more informative than applying the income multiple yourself.
For the complete mechanics of how lenders calculate this, see How Mortgage Affordability Works.
7. Agreements in principle
An Agreement in Principle (AIP), sometimes called a mortgage in principle, is a lender's indicative confirmation of how much they'd be willing to lend based on a quick assessment of your income, outgoings, and a soft credit check. It isn't a guarantee — the full application later involves a hard credit check and detailed verification — but it serves two practical purposes: it gives you a realistic budget before you start viewing properties, and it signals to estate agents and sellers that you're a credible, prepared buyer, which matters in any market where multiple offers are common.
Get an AIP before you start seriously viewing properties, not after you've found one you want to offer on — many estate agents in competitive markets won't put an offer forward without one, and scrambling to get an AIP after finding a property adds avoidable delay and risk of losing out to a better-prepared buyer. See Mortgage Agreements in Principle Explained for the full process.
8. The mortgage process
From AIP to completion, the mortgage process typically takes 4–8 weeks once you have an accepted offer on a property, though this varies with lender workload, property type, and how quickly you can supply the required documentation.
Before viewing seriously — gives you a realistic budget and demonstrates credibility to sellers.
Then submit the full mortgage application, with the specific property details.
Typically 3 months' payslips or accounts (if self-employed), 3 months' bank statements, ID, and proof of deposit source.
The lender arranges a valuation to confirm the property is worth at least the purchase price — this protects the lender's security, and is distinct from (and less thorough than) a buyer's own survey.
The lender's underwriters complete full verification and, if satisfied, issue a formal mortgage offer — this is the document your solicitor needs to proceed to exchange.
Once contracts are exchanged, a completion date is set. Funds transfer and the property legally becomes yours on completion day.
The most common causes of delay sit outside the mortgage process itself but still slow it down: a slow chain elsewhere in the transaction, a valuation that comes back lower than the agreed purchase price (requiring renegotiation or a larger deposit to bridge the gap), or missing documentation that has to be chased and resubmitted. Submitting complete, accurate documentation at the first attempt is the single biggest factor within your control for keeping the timeline to the lower end of the 4–8 week range.
9. Remortgaging
A mortgage doesn't end at completion — it needs active management for as long as you hold it. When your fixed or discount deal ends, you automatically revert to the lender's Standard Variable Rate unless you remortgage beforehand, and in 2026 the gap between SVR (7.5–8.5%) and competitive fixed rates (4.1–4.5%) is wide enough that this single piece of inaction can cost hundreds of pounds a month.
The right time to start the remortgage process is 3–6 months before your current deal expires — early enough to compare the market properly and complete before you're exposed to even a single month at the SVR. For the complete remortgage playbook including the savings calculator, product transfer vs full switch, and the ERC break-even calculation for leaving a deal early, see the Remortgage Hub and What Happens When Your Fixed Rate Ends.
10. Overpayments
Most UK mortgages allow overpayments up to 10% of the outstanding balance per year without triggering an Early Repayment Charge, and even modest, consistent overpayments can meaningfully reduce both the total interest paid and the remaining term — because they reduce the capital balance interest is calculated against earlier than the scheduled amortisation would.
Whether overpaying is the right choice depends on what else you'd do with the same money — clearing higher-interest debt or building an emergency fund generally takes priority over mortgage overpayment, and for some borrowers, investing the money elsewhere may produce a better return than the interest saved. For the full decision framework, see Should I Overpay My Mortgage? and model your own numbers with the overpayment calculator.
11. Common mistakes
Fees, the term length, and the total cost over the deal period all affect which mortgage is actually cheapest — not just the advertised rate.
This adds avoidable delay exactly when speed matters most, and weakens your position against better-prepared competing buyers.
New credit applications, large unexplained deposits, or job changes shortly before a mortgage application can all complicate or delay underwriting.
One of the most expensive and entirely avoidable mistakes — set a reminder 4–6 months before your deal ends, every time.
Exiting a fixed deal early can be the right call if the new rate saves enough to clear the exit penalty within a reasonable period — but check the maths first, not after.
Most lenders want 2–3 years of accounts or tax returns for self-employed applicants, not the single recent payslip a salaried applicant might provide — start gathering this well before you plan to apply, particularly if your accountant needs lead time to prepare figures.
12. Government schemes
A small number of government-backed schemes remain active in 2026 to help specific groups onto the property ladder, most notably aimed at first-time buyers. These generally fall into three categories: savings incentives (such as the Lifetime ISA bonus on funds used toward a first home), shared ownership schemes that let you buy a percentage of a property and pay rent on the remainder, and high-LTV guarantee schemes that encourage lenders to offer 95% mortgages by reducing the lender's risk on the portion above standard lending thresholds.
These schemes change more frequently than almost any other part of the mortgage landscape, with eligibility criteria, thresholds, and availability shifting from one Budget to the next. Rather than duplicate a list here that can go stale quickly, the full current scheme breakdown — including which are still active, eligibility, and key limits — is maintained in the Complete First-Time Buyer Guide, since these schemes are overwhelmingly first-time-buyer-focused.
13. Frequently asked questions
How much can I borrow?
Most lenders offer up to roughly 4.5–5 times your gross annual income, though your specific maximum depends on existing debt, dependants, and how you perform against the lender's stress test. Get an Agreement in Principle for an accurate, lender-specific figure rather than relying on the general multiple alone.
Should I use a mortgage broker or go directly to a lender?
A whole-of-market broker can access deals across many lenders and is particularly valuable if your circumstances are anything other than straightforward — self-employed income, an imperfect credit history, or a specialist property type. For a simple, clean application, going direct can occasionally save the broker fee, but you'll only be seeing that one lender's products rather than the whole market.
What happens if my mortgage application is declined?
A decline from one lender doesn't mean every lender will decline you — different lenders weight income, credit history, and property type differently. Ask for the specific reason where the lender will provide one, address anything correctable, and consider a broker who can identify lenders whose criteria better match your circumstances before reapplying.
How much is an Early Repayment Charge likely to cost?
ERCs are typically structured as a declining percentage of the outstanding balance across the fixed term — for example 5% in year one, tapering to 1% by the final year of a 5-year fix. On a £200,000 balance, that's £10,000 in year one versus £2,000 in year five for the same percentage structure. Always check the specific ERC schedule in your mortgage offer document — they vary by lender and product, and the exact figures should be confirmed before assuming any early exit is or isn't worthwhile.
Can I switch lenders after getting an Agreement in Principle but before completion?
Yes — an AIP is not a binding commitment to that lender, and it's reasonably common to switch if a better rate becomes available, your circumstances change, or the original lender's full application reveals an issue. Switching does mean restarting the formal application and valuation process with the new lender, which can add a few weeks, so it's worth weighing the rate improvement against the potential delay if your transaction is time-sensitive.
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