www.moneysavingexpert.com

If you're on a capped tariff there's usually a lock-in penalty. Therefore the equation is quite simple - will you save enough by ditching and switching to make up for the cap penalty?

The answer depends on what you're being charged and how long you have to go. To help we've a full guide to take you through switching when you're on a fixed tariff or if yours is coming to an end. Read the Capped Tariff Switching guide.

Any home with at least one resident aged over 60 can access Eon's special Staywarm dual fuel tariff, which sadly isn't included by the comparison sites. Uniquely, the bill doesn't depend directly on the energy specifically used - you pay a fixed tariff over a year. This gives peace of mind that if you turn the heat up, you won't pay more.

Once this was a corking tariff that everyone eligible should consider. Now for most people the tariff is priced so high that it simply isn't worth it. Yet it is worth a quick check to see how much it would cost you and if it's within 5% of what you'd pay anyway, you may consider it - see the Staywarm additional briefing.

This is a commonly asked question, as unlike most energy companies and resellers Utility Warehouse operates by network marketing, which means its customers are encouraged to sell on the product to their friends and they get commission for it.

This tends to mean it does well on feedback charts, as customers have a vested interest, and many of them are evangelical about the firm. That in itself doesn't make the product bad, but in our view it is no better or worse than any other energy provider.

Utility Warehouse's prices are included in all the main comparison services we list; therefore if the company turns out to be cheapest for you it should be listed by the comparison sites, and then it's worth going for.

The main pitch of Utility Warehouse is that you can also get cheap mobile, broadband and home phones with it and that reduces the fee. In general we find using the standalone cheapest providers undercuts this, so always compare with those before signing up to it. See the Cheap Home Phones, Cheap Broadband and Cheap Mobiles guides for more.

Luckily green tariffs are now almost commonplace; most suppliers offer them. Green tariffs are defined by the fact that they're either ecologically produced or a proportion of the money is put towards ecological sources.

Yet this is one area where going green and saving money diverge, so it really is a question of your personal politics. The cheapest green tariffs tend to cost more than the cheapest standard tariffs.

However if you can afford to go green, then it's a help to the environment, and if you do, then you can still compare green tariffs, all of the main comparison services allow you to do this.

What counts as green?

This has been disputed for a long time, and some companies made some relatively shoddy claims to being environmentally friendly.

Yet in Feb '10 a new scheme launched to provide proper certification for green tariffs. To be certified under the scheme, suppliers will have to demonstrate their schemes are green to an independent panel of experts, in addition to obligations. You can see a full list of certified tariffs on the Green Energy Scheme website.

There is an open market rule, which means you can switch as often as you like (barring exit penalties on capped tariffs), though of course it's a hassle. Plus it usually takes at least a couple of months for a switch to take place.

It's worth doing a regular check-up of your energy bill to see if you can save though, and we'll include periodic reminders of this when it's a good time to switch in the weekly email.

It's also worth noting that until late 2007 energy companies weren't allowed to lock you in. The regulator Ofgem then decided the market was competitive enough so companies can now require you to sign up for a year's contract.

While it sounds strange, you may save money even if your bills go up! In a period of regular price rises, switching often doesn't mean you actually pay less, though the comparison services will tell you so.

The point is if you're saving 10% when all energy prices are increased by 20%, you'll still pay more than you were, yet less than if you hadn't switched.

This is a nasty sales trick. They offer to cut your monthly outlay by lowering your direct debit, yet that DOESN'T mean you pay less. You should always compare on rate.

Lowering your direct debit just means less outlay each month, but you'll need a massive catch up at the end of year, and could owe it serious cash. See the Fight energy direct debits guide for more.

The cheapest supplier for you is calculated by a complicated algorithm which depends on where you live, and the quantity and type of energy you use. Web and phone based comparison services do this for you.

Just plug in your address and usage (use the Kilowatt hours on the bill rather than the cost to improve accuracy) and they tell you which supplier is cheapest. Yet even if you don't have a bill or have just moved in, most comparison services can still estimate for you.

Comparison services are paid between £30 and £60 per switch by the energy companies; in other words they're referral businesses. In itself this isn't actually a problem, as it doesn't add costs to the consumer, plus the official watchdog Consumer Focus has an accreditation system for website (not phone) services, setting minimum standards.

Yet these are commercial beasts, and thus there are differences between them - in functionality, inclusion of niche players and the treatment of 'initial discounts', and some concerns that one or two tweak results at the edges for their gain.

Yet overall, it's better to use them, than to simply listen to the energy companies when they tout 'we're cheapest'.

In the early days of the site, way back in 2004, a comparison service boss asked me, 'how can we be your top pick?' Flippantly, I replied 'pay customers some of your cut!' and surprisingly it agreed to a trial, but only for users of this site, so as not to cannibalise its existing custom.

That was the start, and as this site's grown, now with many millions of users a month, they all want a piece of the pie. Hence many now offer cashback.

Yet still in the main it's only links from this site, or for those who use the phone service and quote the deals here. If you go direct you get exactly the same service but without the cashback although you may be able to get cashback for specific energy providers via Cashback Websites.

It's quite common to use different comparison sites and get different results. While it can be annoying, not much can be done to standardise it. The main reasons it happens are:

• These sites make a number of assumptions.
  
  If you haven't entered Kilowatt hours, which is the most accurate way, then just giving a past bill can't actually tell the comparison sites your exact usage, so they each make some assumptions to work it out. Slight differences in those assumptions can impact the overall recommendations.
  
  Even if you do put Kilowatt hours in, other assumptions are made, as some sites add in seasonal usage weightings and more slight variances due to how the calculations are done. Of course it's very frustrating, but ultimately it's likely the actual difference in what you pay will be small.
• Check you've selected exactly the same current tariff.
  
  Annoyingly when asking which tariff you're currently on comparison sites often list almost identically named products for each provider - something that should be cracked down on - so make sure when you're picking your current tariff, you get it exactly right.
• Was the difference just in the amount saved?
  
  If the tariff you should switch to is identical, but the saving isn't, this is less of a worry - it's far more likely to be about assumptions.

What about when there are genuinely different answers?

That's very annoying and really it shouldn't happen, but occasionally it does. The only way to get PERFECT accuracy is get a spreadsheet out and do your own comparisons. But unless you're a maths whizz with a lot of time that's virtually impossible.

The actual answer here is to remember the differences are only at the margins, so overall if you're making a saving it's still a good move.

Why do we suggest comparison sites if this can happen?

The alternative is listening to the guy in the supermarket or knocking at your door trying to flog you a new tariff, and they're just salespeople. While the comparison sites are far from perfect, they are accredited by energywatch and those standards mean the differences are small.

In 2005, we took the decision (having made a big fuss about it), that ultimately it's more important to encourage people to save big money by getting the best tariff easily and switching at the right moment, than to berate comparison sites for small differences.

Thus I accepted comparison sites are the 'least worst' way to do it. Overall they provide a good service and tell you roughly the cheapest provider. It's my hope they'll be improved, but they're much much better than sticking with an expensive supplier and watching prices rise.

We're being asked this a lot, we focus on consumers, so it's not really our bag, yet just like domestic energy bills, it's possible to compare and switch to cheaper providers. The right comparisons to use depend again on what type of business you are running.

Limited companies (or anyone with commercial premises)

Here you're limited to using special business tariffs, but luckily some of the top energy price comparisons have cottoned on to the small business market.

However while there are websites, for their business comparison services most tend to operate through callback systems (ie you request it calls and goes through the savings with you), not online.

Top comparisons for small biz

The savings possible are huge though, for a sample postcode we tried in the North West of England an annual electricity bill of £3,500 using the regional electricity company, it was possible to cut the bill to £2,300, a saving of £1,200!

The key rules for small businesses

• Be extremely wary of renewal dates. Most business tariffs are fixed contracts for 1-5 years. Sneakily if you don't tell your supplier you want to move within 30 days of the end date of your tariff it will roll you onto another contract which you will be stuck with, usually at a higher cost.
• Get off default tariffs. If you're not on a fixed contract, you're on a supplier's default tariff which is hugely expensive in comparison. Use one of the comparisons above to get off it asap.
• A good credit rating gets better rates. Most suppliers require a fairly good credit rating before it offers you a deal. So the better your credit history, the more cheap deals you'll have access to. If you don't have one or are a start-up company, you may have to pay a lump sum up front to secure a deal.

Sole trader? (i.e. working from a house)

If you are working on a small scale, eg. in your own or a colleague's home, and are a sole trader, you can usually deduct a proportion of your household bills as a business expense.

Switch the house to the cheapest gas and electricity providers using the top standard price comparisons (plus get cashback), using the normal Gas & Electricity switching technique.

Independent Gas Transporters (IGTs) are often used by constructors instead of National Grid (previously called Transco) in new build properties as they charge less to fit pipes. One in twenty people are supplied by them instead of Transco.

If that's the case, you may have to pay £30-£70 more on top of any comparison quote as the gas provider uses both pipes, so must pay Transco and the IGT to supply gas to your house. This charge is passed directly on to you.

If the MPRN (the meter point reference number, unique to your house) on your bill is 10 digits long and starts with 74 or 75 this means you are supplied by an Independent Gas Transporter. If you're not sure, Energylinx has a useful tool you can use to check.

Switching at the right time can save you around £200/year, so you should still save. All providers, except British Gas, charge if you have an independent gas transporter; so simply do a comparison and if it's less than £40 compared to the cheapest provider opt for it instead.

Occasionally it may mean you can't switch to certain suppliers.