While I tend to be fairly organised with plotting holidays and make sure I take my full allowance from work every year, research from TravelSupermarket revealed that a staggering 1.2million Brits hadn't taken the time they were legally owed at the end of 2012.

Collectively, this lost them 6.2milllion days of 2012 annual leave – an average of six days per employee.

But why are Brits skimping on days out of the office? We take a look at some of the most common reasons – and explain why none of them are good enough to avoid your full annual leave.

“I’m too busy to take time off”

More than one-in-four British employees (21%) felt they were simply too busy at work to take time off.

And, as Bob Atkinson, TravelSupermarket’s travel expert explains, economic uncertainty is only adding to our reluctance: “As we head out of a double-dip recession, it’s no surprise that people are wary about taking all their leave, especially if they feel pressure and uncertainty at work.

"Athough unemployment figures have slightly dropped, the research from TravelSupermarket highlights that not everyone is completely convinced that the economic bounce-back is permanent.”

But days out of the office might actually help…

While you may feel guilty being out of the office, days away from your daily grind can actually make you more productive while you are in work.

A few days away from your daily routine – whether you are sunning yourself on a beach, exploring a city or just catching up on your unwatched DVD box-sets at home – will recharge your batteries.

The chances are, after a break, you’ll return to work with more energy and focus and you may just look at the task that seemed overwhelming before you went away in a different light.

So, rather than looking disapprovingly at your annual leave, your boss may just thank you for returning to the office with more enthusiasm rather than burning out at your desk.

“I don’t have anything to do on my days off”

I conducted a quick straw poll among my MoneySupermarket colleagues and asked them whether they booked all of their annual in 2012 and, if not, why not.

A common response from those who hadn’t booked all of their days off was that they didn’t have anything specific to do, so didn’t want to “waste” the day off.

But, this can be a dangerous tactic as if you leave booking your days off until the last minute when you’ve found something to do, you risk not being able to take the days you want – or fitting in any at all – as other colleagues will have got their requests in first.

If this sounds like a familiar predicament, Bob Atkinson suggests thinking more creatively about your holiday allowance: “Splitting days up can be a great way to make the most of your weekends.

"Taking a Monday or Friday off means you can go on a shopping break to Europe or the Mediterranean, for example, without being stressed about cramming everything into two days then returning to the office exhausted on the Monday.”

Think of the quality time you are throwing away with friends and family

When was the last time you spent some quality time with your friends and family? If the answer is a long time ago, use the days off you don’t have plans for in 2013 to enjoy their company.

Increasingly the stresses and strains of daily life get in the way of our relationships so, the next time you decide that you don’t have anything to do, use your spare days to devote some time to a loved one.

“I just haven’t got round to booking my days off yet”

If this sounds like you, put booking holidays on your work to-do list and treat it like a task as you would any other deadline. Not only will this prompt you to book your full allowance, your boss and colleagues will thank you as it will help your whole team plan the year more effectively.

Plus, as soon as these days are booked into your calendar, you’ll have something to look forward to which is likely to result in a lift of your mood as you have something to aim for.

Would you give part of your salary away?

Remember that your annual leave allowance is part of your rewards package from your employer and, as with your wage, the more you work, the more you are entitled to. You wouldn’t willingly give part of your salary away, would you?

Well, that’s exactly what British employees are doing and TravelSupermarket’s research revealed that, as a nation, we gave a huge £697million away in free work days to our employers in 2012.

So, the next time you decide to forgo a day off, think of the money you are giving away.

“My work won’t get done while I am away so I may as well stay in the office”

Many employees worry about the piles of work and emails they will come back to after a week or two off and decide that staying in the office is the easiest option.

If this is your concern, talk to your manager about who the best person to delegate your work to while you are off is or, if you are managing a team, think about who you can ask to pick up important tasks up for you.

Just remember, I’m currently not in the office and my article has been edited, published and made its way in front of you…

Please note: Any rates or deals mentioned in this article were available at the time of writing. Click on a highlighted product and apply direct.