IN JANUARY, for many, the letterbox becomes an enemy. When it flips open it contains a bill. And the worst of those for many are credit cards - a final reckoning of the last year’s debts, topped off by Christmas spending. If you’ve debts you can’t repay, there are two key things to do: stop borrowing more and cut the interest rate.

By cutting the rate, more of your repayments clear the actual debt rather than just help add profit to the lender. The main weapon to clear credit and store cards is a balance transfer, where you get a new credit card(s) that repays debts on existing cards for you, so you owe it, but at a far lower cost, for a small fee.

The good news is right now there’s white hot competition in this market. So sort it now and stop paying more than needed. And if you won’t listen to me, listen to Marc who emailed: “took your tip on taking a balance transfer card and we’ve saved £9,400 over the next 40 months. Amazing.”

l How to choose the right balance transfer card deals

There are a vast range of cards to choose from, ranging up to 43 months 0%. But it isn’t quite a simple as just go for the longest.

1. Go for the lowest fee in the time you’re sure you can repay. Most cards charge a one-off fee on the amount of debt transferred. So, for example, 3% is £30 per £1,000. Generally, the longer the 0% period, the bigger the fee.

So what you need to do is calculate how long you think you’ll take to clear the debt, add a few months for safety, then pick the lowest fee within the time you need. If you’re not sure, play safe and go long.

For example, the longest card available at the time of writing is the www.MBNA.co.uk up to 43 mths 0%, with a 3.29% fee. The longest no-fee card is www.Halifax.co.uk up to 26 mths 0%.

2. You need a personalised best buy table. Each lender credit scores you differently, where one accepts, others reject. Best buy tables just list the best offers available, but what really counts is what you can be accepted for. Worse still, the only way to find out what you’ll actually get is to apply, and that marks your credit file.

Yet we’ve seen a new range of tools that show your likely chances of acceptance before applying, protecting your credit score. Some card firms have their own or my Eligibility Calculator (www.mse.me/BTeligibility) shows your chances for most top cards, effectively giving you a personal best buy table.

3. Many cards are ‘up tos’.

With these cards, only 51% of accepted applicants need get the advertised 0% length, the rest could get a shorter deal. So, in many cases, the cards that aren’t ‘up tos’ can be better. The longest non-up to 0% deal is www.SainsburysBank.co.uk 42mth 0% for a 3.5% fee, and it also has the longest fee free deal at 25mth 0%.

This is especially important when you do a eligibility comparison. If all your accepted cards are ‘up to’ cards, then the likelihood is you won’t get the full 0%. So even if there’re one or two non ‘up to’ deals there, they may be worth looking at.

l The three balance transfer golden rules

Getting the right card’s only half the job. Once you get it, you need to use it the right way.

a) Repay at least the set monthly min, or you can lose the 0% deal. The same can be true if you bust your credit limit.

b) Always clear the card or shift again before the 0% ends, or rates jump to the representative APRs, typically 18% to 20%.

c) Don’t spend or withdraw cash on them, it’s rarely at the cheap rate. Instead, shift your debt to these cards, then put it away somewhere not to be used.

A final thought on this. The best way to clear debts is to repay as much as you can and be wary of only repaying the minimum repayments. That’s dangerous. Minimum repayments are set to only just cover the interest, so repayments drop as debt drops, prolonging the debt period.

For example with £3,000 on a typical card, repaying minimum repayments it’d take you 27 years to repay, costing £4,000 in interest. Now you may say to me “I can’t afford to pay more”. Yet in the first month the minimum repayment would be about £70, and if you fixed your repayment at that rather than letting it drop, you’d clear the debt in five years.

Yet if you’ve multiple debts, order them in terms of interest rates, and throw all spare cash at repaying the one with the highest rate (as its growing fastest). Just pay minimums on the rest. Once that’s clear, focus on the next most expensive debt and so on.

l Are you in debt crisis?

The solutions above are for those who can manage their debts. Yet if you a) can’t meet even the minimum monthly payments b) have non-mortgage debts bigger than a year’s salary or c) can’t sleep due to your debts, or have depression or anxiety because of them, then you’re in what I define as debt crisis.

Forget the above and get free, one-on-one debt-counselling help from www.CitizensAdvice.org, www.capuk.org, www.StepChange.org or www.NationalDebtline.co.uk. They are there to help, not judge. The most common thing I hear after is: “I finally got a good night’s sleep”.