01Check your odds before you apply
Before you apply for a 0% balance transfer card, run a free eligibility checker. It does a soft search, shows roughly how likely each card is to accept you, and leaves nothing on your file that a lender can see.
This matters because the application is the risky part. A full application triggers a hard search, and a hard search stays on your file whether you get the card or not. Get turned down for the headline 36-month deal, apply for another, get turned down again, and now you have two marks working against you for the next one.
So the order is simple: check first, then apply once, for the card you are most likely to get. Every tool below does the soft-search check. The best one to start with is MoneySavingExpert's eligibility calculator, but it helps to know what each is actually for.
02Soft search vs hard search
A soft search is a quiet look at your credit file. You can see it when you check your own report, but lenders can't, and it has no effect on your score. Every eligibility checker on this page uses one.
A hard search is the opposite. It is recorded, lenders can see it, and a cluster of them in a short space of time pulls your score down and makes you look like you are chasing credit. One or two across a year is normal. Five in a month is a warning sign to the next lender.
One thing an eligibility checker can't do is promise you the card. It gives you odds, and sometimes a "pre-approved" result, which means you will get it subject to the lender's ID and fraud checks. Even a 90% result can be declined on the full application. Treat it as odds, not a contract.
03Where to check, for free
MoneySavingExpert's eligibility calculator is the one to start with. It is free, part of the free Credit Club, and gives you bespoke acceptance odds for specific balance transfer cards rather than a vague score out of 999. Some results come back pre-approved. You apply for the card through the same tool, so you spend your one hard search on the card you are most likely to get.
ClearScore is free for as long as you want it. It shows your Equifax data and a built-in checker for cards and loans you are likely to be accepted for. Useful if you want to watch your file over time, not just before one application.
Credit Karma and TotallyMoney do the same job off your TransUnion file: free score, free report, and card matches based on your real data. They earn their money as brokers when you take a card, which is why they cost you nothing.
The comparison sites have soft-search checkers too. MoneySuperMarket, Compare the Market and Uswitch each show which balance transfer deals across the market you are likely to get, in one sweep.
Most card issuers, including Barclaycard and HSBC, have their own eligibility checker. Worth a look if you already have one card in mind, though it only tells you about that single lender.
04Seeing what lenders actually see
Eligibility checkers tell you your odds. They don't show you the detail behind them. If you keep getting low odds and can't see why, or you have something big coming up like a mortgage, look at the file itself.
CheckMyFile gives the most complete view because it pulls all three UK credit agencies, Equifax, Experian and TransUnion, into one report. Most free apps only show one. It is a free 30-day trial, then £14.99 a month, so set a reminder and cancel inside the trial if you only need one look. It doesn't match you to cards. It is for reading the file.
If you would rather stay free, you can cover all three agencies with three free tools: ClearScore for Equifax, Credit Karma or TotallyMoney for TransUnion, and the Experian app for a free monthly Experian score. More logins, no cost.
05If the odds come back low
Low odds across the board aren't a verdict on you. They are the file telling you it is worth a few months of groundwork before you apply, so you don't spend hard searches on cards you won't get.
The lever that moves fastest for a balance transfer is utilisation: how much of your available credit limit you are using. Getting your cards well under half their limit, and lower if you can, tends to help more than almost anything else in the short term. Being on the electoral roll, no missed payments, and spacing out applications all add up too.
That is also the quiet logic of a payoff plan. As the balances come down, your utilisation drops and your odds go up. Paying the debt down is the same move as becoming eligible to refinance it.
06Once you know your odds
Pick the card with the best odds and the longest 0% window you can realistically clear, and apply for that one. Then the real work starts: clearing the balance before the promo ends, because the rate afterwards can jump to 25% or more on whatever is left.
Work out the monthly payment that clears it in time and treat that as the bill, not the minimum. Our balance transfer guide covers whether a transfer is worth it for your numbers and has the calculator to set the target. If you are still weighing it up, start there.
And if you are struggling to keep up with even minimum payments, a new card is not the answer. StepChange (0800 138 1111) gives free debt advice and won't try to sell you anything.