Credit scores, on which lenders will decide whether or not to accept your application for a mortgage, can take years to clean up if you have had past financial difficulties.

Even if you haven’t but are relatively young or have few financial commitments, it takes time to build up a decent score – but doing so will increase your options and reduce the cost of borrowing.

However, it is sometimes not clear how the algorithms responsible for your credit score work. Some seemingly wise decisions could affect your score negatively, while others might imply that you are inexperienced with handling debt.

Of course, there are circumstances seen as an immediate red flag and for the most serious you may just have to wait it out. Bankruptcies and court judgements will take years to be expunged from your record, so there is little point in applying for a mortgage while they remain.

Even a missed or late payment can stay on your record for six years – no matter how small or accidental – although its negative effect will diminish over time.

If it is a mistake, you can ask the original lender to remove it. If it isn’t, you can explain any mitigating circumstances by adding a “notice of correction” – but lenders may not take this into account.

Frequently changing bank accounts, phone contracts, utility providers and credit card deals to get the best rate may all seem pretty canny, financially. But each will leave a search on your record, and too many of these in the year before a mortgage application could impact negatively. Better to leave the deal chasing until after you have been approved.

Having too much unsecured debt will also count against you – it will vary from person to person, but as a general rule of thumb, £15,000 in loans or on credit cards is seen as high, even if you are managing the debt well.

Other seemingly innocuous lending could affect your score too. There are a host of buy-now, pay-later plans available for shopping, which offer interest-free loans over a few months. While normally keeping your savings and making easily affordable repayments for a new sofa is sound financial practice, some of these offers share their information with credit companies.

Equally, you might think that living without credit is admirable, but using a credit card wisely will bump up your score.

The advice is to try to use around a third of your available credit, paying it off each month. More than 60 per cent is seen as questionable.

Never withdraw cash on a credit card, it incurs extra charges and is seen as a mark of the impetuous.

For a perfect score, be ready to dump your friends and relations, financially at least. Joint accounts with ex-partners or flatmates can hugely impact your credit score if their pecuniary arrangements aren’t as squeaky clean as yours.

Most importantly, it is a good idea to keep checking your credit score with one of the free services on a regular monthly basis.

If you can curate, hone and nurture your credit score, you’ll be a step ahead when it comes to securing the best mortgage rate.

- Kirsty McLuckie is property editor at The Scotsman

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