7 Mortgage Mistakes First-Time Buyers Make (and How to Avoid Them)
- Brian Swint
- 36 minutes ago
- 7 min read
Buying your first home is exciting. It's also confusing, emotional, and full of things nobody explains until you're already deep in viewings, WhatsApp messages from estate agents, and that strange new habit of checking Rightmove before bed.
At Delta Mortgages, we see the same mistakes again and again. The good news is that none of them are unusual, and all of them are avoidable…with a little thought and preparation.
This guide covers the top 7 first-time buyer mortgage mistakes in the UK, why they happen, and exactly how to avoid them.
You know, the stuff that actually helps. Let’s dig in.
The mortgage mistakes first-time buyers make most often (and why they happen)
Most first-time buyers have their act together. The problem isn't common sense. It's that the mortgage process is full of moving parts, and it's rarely explained in one clear place. One person talks about rates. Someone else talks about deposits. Then a lender asks for documents you didn't know existed.
The hidden cost of getting it slightly wrong
A mortgage mistake doesn't usually mean you can't buy. It might mean:
you get offered less than expected, so you lose a property you could have bought with better prep
your mortgage application takes longer because a lender needs more checks
you choose a deal that looks cheap on rate, but costs more once fees are factored in
you end up paying more later if you drop onto your lender's Standard Variable Rate (SVR)
A few early decisions can save you time, money, and a lot of unnecessary stress. Here's what to watch out for.
Mistake 1: Starting house hunting before knowing your numbers
Scrolling Rightmove feels like the natural first step. And it's fun. But it works better when you already know what you can afford, rather than falling for a house that's £50k outside your budget. (We've all been there.)
Before you book viewings, get three things clear:
Your deposit (and where it's coming from). If any is a gifted deposit from family, that's completely normal, but lenders will want clarity and a clear paper trail.
Your realistic budget (not just the maximum). A lender might offer a maximum based on an affordability assessment. That doesn't mean you should borrow it. "Maximum" is not the same as "comfortable".
Your monthly comfort zone. The number that lets you sleep at night, including bills, childcare, subscriptions, and the occasional takeaway.
The "I can afford it" trap (and what lenders look at)
Lenders don't approve mortgages based on what you're paying in rent. They run an affordability assessment looking at your income, committed spending, and whether you could cope if rates rose (known as stress testing).
Things that often reduce borrowing include car finance, childcare costs, credit card balances (even if you pay them off), and higher day-to-day spending. Yes, they notice the coffee subscriptions.
Simple steps to avoid this mistake
Work out your comfort-zone monthly payment first, then build your search around it.
Make sure your deposit is clearly evidenced, especially if any is gifted.
Speak to a mortgage broker early for a realistic view of what lenders will accept.
Mistake 2: Skipping a Decision in Principle (DIP)
A Decision in Principle is a lender's early indication of how much they may lend you. Think of it as your golden ticket for house viewings. Without one, you're just someone who likes looking at kitchens.
A DIP matters because:
It makes your offer stronger. Estate agents take you more seriously when you're not guessing your budget.
It reduces surprises later. You'll get an early steer on how your finances land with a lender before you're emotionally invested in a property.
It speeds things up. You're already part-way through the information a lender will need for the full application.
Most DIPs use a soft credit check, which doesn't affect your credit score. Some lenders use a hard check, so it's worth asking first.
📝 A quick note: a DIP is not a mortgage offer. It's a helpful first step, not the finish line. But it's one of the simplest ways to make your search feel less like guesswork.
Simple steps to avoid this mistake
Get a DIP before you start booking lots of viewings.
Ask whether it uses a soft or hard credit check.
Avoid multiple DIP applications in a short period unless advised to.
Related Insight: What is a Mortgage in Principle – and Why It Matters?
Mistake 3: Forgetting the true cost of buying
The property price gets all the attention. But the extra costs are usually lurking in the background, ready to take a chunk out of your savings if you haven't planned for them.
Costs first-time buyers commonly underestimate:
Professional fees: solicitor/conveyancer, survey (HomeBuyer Report or Building Survey)
Lender fees: arrangement fees (sometimes added to the loan), valuation fees, mortgage broker fees
Moving costs: removals, buildings insurance (often needed from exchange), set-up costs like white goods and furniture
Some first-time buyers will also pay Stamp Duty, depending on the purchase price and current thresholds.
💡 The key point: most of these costs need to come from savings. They're not something you can roll into the mortgage at the last minute. Treat your deposit and your buying costs as two separate pots from day one. Future you will be grateful.
Simple steps to avoid this mistake
Get a realistic buying costs estimate early, before you start viewing seriously.
Get an initial solicitor quote and include it in your budget.
Keep money aside for moving and set-up costs, separate from your deposit.
Mistake 4: Choosing a mortgage based on rate alone
It's natural to fixate on the mortgage rate. Comparison sites make it feel like the only thing that matters. Lowest number wins, right?
Not quite.
A first-time buyer mortgage isn't just a rate. The total cost depends on the full package:
Product fees (often called arrangement fees)
Overpayment allowances (useful if you want flexibility to pay down the balance)
Early Repayment Charges (ERCs) (important if you might move or remortgage sooner than planned)
Porting options (whether you can take the deal with you if you move)
A simple example
• Deal A: slightly lower rate, £1,499 arrangement fee
• Deal B: slightly higher rate, no fee
If you're borrowing a smaller amount, that fee can outweigh the rate saving. And if you add the fee to the mortgage, you pay interest on it too. Suddenly, Deal A isn't looking quite so clever.
A mortgage broker will compare the total cost over the fixed period, so you see what you're actually paying.
Fixed vs tracker vs variable
Fixed rate: your rate stays the same for a set period (commonly 2, 3, or 5 years). Good for stability and sleeping soundly.
Tracker: your rate moves with the Bank of England base rate. Payments can change. Excitement not guaranteed.
Variable: the lender can change the rate. This includes the SVR most borrowers move onto when a deal ends. This is why remortgaging before your deal ends matters.
Simple steps to avoid this mistake
Compare deals by total cost over the fixed period, not rate alone.
Check the ERCs and overpayment rules.
If you may move within a few years, ask about porting.
Mistake 5: Credit file issues they didn't know existed
This one catches a lot of sensible people out. Not because they've been reckless, but because credit files can be oddly picky about things you'd never think to check.
Lenders look at your credit history to understand how you've handled borrowing and bills. You don't need a perfect score, but you do need a clean, consistent story.
Common "I had no idea that mattered" issues:
Old or incorrect addresses (that flat you forgot to update three years ago)
Not being on the electoral roll
Missed or late payments you'd forgotten about
High credit utilisation (using a large chunk of your available credit)
Lots of recent credit applications
Financial links to someone else (like an old joint account with an ex)
None of these automatically means you'll be declined. But they can affect which lenders will consider you and what rates are available.
Simple steps to avoid this mistake
Check your credit file early (all three agencies can differ).
Make sure your address history is consistent.
Register on the electoral roll at your current address.
Avoid new credit applications in the run-up to your mortgage application.
Mistake 6: Underestimating affordability checks
Many first-time buyers assume a mortgage is mainly about income and credit score. In reality, the affordability assessment is often the biggest deciding factor. And it can be stricter than you'd expect.
When a lender stress tests you, they're asking: if rates rose, could you still afford the mortgage? They run your figures through a higher "stressed rate", not just today's rate.
That's why you can feel confident about the numbers, then find a lender offers less than expected. It's not personal. It's just maths (their maths, specifically).
Common things that reduce borrowing:
Credit commitments (car finance, loans, buy-now-pay-later)
Childcare and dependants
Student loan deductions
Subscriptions and regular outgoings
Day-to-day spending patterns
A big misconception is around credit cards. Even if you clear the balance monthly, lenders may still assume a repayment based on your limit.
Simple steps to avoid this mistake
Get a realistic view of affordability based on your actual outgoings, not just your salary.
Reduce or clear high-interest debts where possible before applying.
Keep bank statements stable for a few months: no big unexplained transfers, no last-minute borrowing.
Mistake 7: Leaving everything until the last minute
This is one of the most avoidable mistakes, and it's rarely about laziness. It's usually because buyers don't realise how many moving parts sit behind a mortgage application.
Spoiler Alert: it's a lot.
When you find the right property, things move quickly. Before you make an offer, it helps to have:
A DIP in place, so you can show you're ready to proceed
A clear deposit trail (funds in a UK account, clearly evidenced)
A mortgage adviser and conveyancer ready to go
Once your offer is accepted, most delays happen while lenders and solicitors wait for documents. A few rules keep things moving:
Respond quickly to document requests (even if it's just to say when you'll send them)
Keep your finances stable (avoid new credit or big purchases)
Avoid changing jobs mid-application unless discussed in advance
Book your survey promptly
This is where working with a mortgage broker really helps. If your case is already packaged properly, you reduce the back-and-forth and keep the chain moving. Less chasing, more progress.
Simple steps to avoid this mistake
Get your DIP and documents ready before you start making offers.
Keep your deposit evidence tidy.
Line up your conveyancer early so you can instruct them immediately.
Speak to a mortgage broker about getting a first-time buyer mortgage
By now, you'll have a clear picture of the mistakes first-time buyers make most often, and the simple things you can do to avoid them.
If you'd like a calm second pair of eyes on your plan (and someone who won't judge your Rightmove habit), get in touch with Brian Swint for straightforward, no-pressure mortgage advice.
Call 0303 0033 606 or email brian.swint@deltamortgages.co.uk for a free, no-obligation chat.
Whether you're buying in Dorset, Hampshire, Brighton or anywhere across the South, we'll help you get clear on your next step.
Author:
Your property may be repossessed if you do not keep up repayments on your mortgage.