Martin Lewis: 10 things you need to know about credit scoring

The more creditworthy you are, the better deals you can get, whether it be mortgages, contract mobile phones, bank accounts, monthly car insurance or even how you pay for your energy bill.

So it's time to add 'manage my credit file' to your to-do list - especially if you’re about to make a big application. To help, here are my 10 things you need to know about credit scoring.

1. You don't have a universal credit rating - there's no blacklist

Each lender scores you differently and secretly to see if you meet its requirements as a profitable customer. Those whose history shows they're unlikely to repay are unlikely to be profitable, but good risks can be rejected too, if the lender thinks you won't make it money.

2. Boosting your credit score's like going on Tinder

You can try a host of things to make yourself more attractive to lenders, but there's no universal fix. Say two women both use dating app Tinder - one might always swipe no to men with beards, the other might love them. Equally, different lenders look for different things.

Yet most people like someone who doesn’t smell, so here are some simple cosmetic changes that work for most:

a) Evidence of stability's good. Put a landline, not mobile, on applications.

b) Don't withdraw cash on credit cards or get payday loans. They’re expensive and evidence of poor money management.

c) Never miss or be late on repayments. Use a direct debit, even if just for the minimum (then repay more on top).

d) Check for address errors. An old active but unused mobile registered to an old address could cause a mortgage rejection.

e) Time it right. Major problems like CCJs, defaults or bankruptcy stay on your file for six years. Applications for products stay on for one year. If they'll soon lapse, consider waiting to apply.

3. Find out for free what cards and loans you'll be accepted for

Most of the credit score boosting techniques take time to filter through. If you need credit now, instead the key is to find which provider is most likely to accept you.

My free loan and credit card eligibility calculators at moneysavingexpert.com/eligibility show your % odds of acceptance (and unlike applying don’t impact your credit-worthiness), so you can home in on the right card or loan, minimising applications.

They can be hugely powerful. Kelly messaged me to say: "Used the balance transfer eligibility calc and got 35mths 0%, shifted £11,500 from up to 29.9% APR" - saving £4,600 interest.

4. Get on the electoral roll

Register at www.gov.uk. Don't worry about getting lots of junk mail - you can opt out of the 'open register' element, which stops this.

5. Check your file

Even small errors on your files at the three credit reference agencies - Experian, Equifax and Callcredit - kibosh applications. Check them all line by line at least once a year - you've a legal right for £2.

Yet to check them all for free, use noddle.co.uk for Callcredit and sign up to both Experian.co.uk and equifax.co.uk free month long trials of their outrageously expensive credit monitoring services – then once you’ve got your file, cancel asap.

And don’t feel the need to pay to ‘find your credit score’. These are just a lose indication at best. Each lender scores differently and uses far more info than just your credit file.

6. Avoid lots of applications in a short space of time

Almost every card or loan application leaves a file footprint. Too many of these, especially close together, hurt future applications. The system's anti-shopping around, as if you're offered a worse rate than that advertised, you'll want to apply elsewhere.

So space out and prioritise applications. Due a new mortgage? Don't apply for minor things like cashback credit cards a week before.

7. Get unfair defaults removed

If there's a default on your file that isn't fair, for example, if you didn't pay a catalogue loan as it failed to deliver the goods, it's important to get it removed.

First complain to the lender and if that fails, write to the credit reference agency to ask it to add a short Notice of Correction to your credit file. For example, "It was for a swimsuit from a catalogue firm and it never arrived."

This will slow down applications, as most credit companies will review these manually, but a slow yes is better than a "no". Finally, complain to www.financial–ombudsman.org.uk

8. Use a bizarre trick to (re)build your creditworthiness

Rejection's likely if your history makes you look a bad credit citizen, yet lenders can reject those who’ve never had credit due to lack of data.

The answer’s to get a credit card, just to do about £50 a month of normal spending on it (never withdraw cash), then repay IN FULL by direct debit each month so there's no interest. After six months to a year, you'll start to look a better credit citizen.

The catch 22 is ‘how do you get a credit card if you’ve poor credit?’ The answer’s specialist credit rebuild cards - I’ve a full list of cards and help to find which you’re most likely to be accepted for at www.mse.me/creditrebuild

9. Be consistent, even on different applications, to avoid fraud scoring

Fraud scoring is credit scoring's secret cousin. Among other things, these specialist agencies map how consistent your applications are, even to totally different firms. So if you've a couple of mobiles or job titles, use exactly the same one every time you apply.

10. Beware joint mortgages, loans and bank accounts

It's not whether you kiss, live together, hold hands or are married that links credit files. It's simply whether you have a joint credit agreement (mortgages, loans, bank accounts and sometimes utility bills - joint credit cards don't exist).

This means their credit history can be looked at when assessing whether to lend to you. If theirs is bad, avoid any joint products.