Are you ripping yourself off? At least 11m people in the UK are overpaying on their energy bills, usually by £100s a year.

Here's how to know if you one of the 11m massively overpaying:

- Anyone who's with a big 6 company - British Gas, Eon, EDF, Npower, Scottish Power and SSE - and is on their standard tariff (which is almost everyone who hasn't switched in the last year).

Even if you're not with them, as prices have dropped rapidly in the last year, many can still save.

MORE: Martin Lewis of MoneySavingExpert: An urgent warning to anyone who's never owned a homeOne big issue here is many people assume energy companies have one price. They don't. They can have lots of different tariffs - yes that does literally mean they charge different people totally different amounts for the same thing. So the key is to ensure you're one of those being charged less not more.

Of course those willing to move company can save even more. Currently, the cheapest deals on the market are around £830/yr for typical usage. So if you're willing to switch firm, move to that and you could be paying £350/yr less.

- You can't just get these deals - you have to do it the right way.

Energy firms don't just move you to its cheaper deals.

These are generally reserved for proactive switchers. This is all about using a comparison site like my www.cheapenergyclub.co.uk which is whole of market (and includes a 'stick with my existing provider' filter). It also gives £25 cashback per dual fuel switch, which you wouldn't get direct, or any www.ofgem.gov.uk approved comparison sites.

- Switching and saving tends to beat sticking and saving.

My point here isn't that you should stick with your existing provider. Generally the best thing is to do a comparison.

Often you'll find it's firms you've not heard of with no customer service track record that come top as they're trying to build market share.

If that worries you, you can scrolls down to find the cheapest company with a decent customer service reputation (or use 'good customer service' filters if the site has them).

There are lots of mid-sized firms with really good ratings and really cheap prices.

Yet the reason I started with the big 6 deals, is that I know many are scared of switching firm, and as right now we're in a rare sweet spot where you can stick and save, that's a decent option for action.

- Don't worry if you're short of info to do a comparison.

Even if you just know your address and existing providers name you can do it.

Of course it'll be more accurate if you have your exact tariff details and can plug your usage in too.

But overall the sin of inaction is usually bigger than the sin of inaccuracy - so if you don't know the comparison site will estimate it for you.

This will only take you a few minutes. Then it's switched over in 17 days.

And if you're worried about the practicalities of switching - well if you're sticking with the same company, very little changes. Even if you do switch to another company, while it's the same pipes, gas, meter, safety - you don't lose supply - the only difference is price and customer service.

Those on prepayment meters can save too - but not as much.

If you pay by a key or card meter, as many of the country's poorest and most vulnerable do, then outrageously there's nowhere near as much competition, and you pay more - though prices have been capped which has helped a touch. If you do a comparison there are often savings to be made, but often less than £100.

If you can, try and switch to a billed meter. It's free to do with one of the big six providers, and you'll usually be credit scored to check you're capable of keeping up with payments.