Everybody needs to assess their energy bills - urgently. If you don't act soon, you will have missed the window to insure against price hikes.

My prediction of a big energy price hike this summer was correct. Scottish Power is doing just that. In August it will increase gas prices by 19 per cent and electricity by 10 per cent, hitting 2.4 million customers.

Yet make no mistake. Scottish Power won't be alone. Energy companies are like sheep. Where one leads, the others follow. British Gas has already hinted that it plans increases and the Bank of England has said it expects an annual 15 per cent energy rise. It would be a major shock if the other big six didn't follow suit. Of course, one supplier may hold off introducing rises until October in order to gain short term advantage on the comparison sites, but it will probably just be a postponement of a rise, not a cancellation.

Fix now if you can't afford rises

A fix guarantees your rate won't rise for a set period. Two years and many on standard rates will save £150 a year and get the lock-in at the cheaper price (as standard rates are so expensive).

It's an insurance policy against energy hikes

It is possible to get online tariffs even cheaper than the cheapest fix, but these are subject to any rate hikes, and even an eight per cent rise (less than predicted) would mean a fix is cheaper in the long run. And while more rises are not guaranteed, if the thought of price hikes is a nightmare, a fix effectively is an insurance policy against them.

This is all about speed. In the past, once price hikes were announced, the cheapest fixes were soon pulled and replaced with more expensive ones. Add the fact that a switchover can take two months means if you are going to fix, speed is crucial.

Since the price hikes hit, I have been swamped with questions about fixing, so let me answer them here:

How do I find my cheapest fix?

It depends on where you live and usage. Plug your details into a consumer focus-approved comparison site and click the 'show only fixed tariffs' tab. Or to get up to £40 added cashback on top of your switch see www.moneysavingexpert.com/gaselec

Is Scottish Power's new price on comparison sites?

Yes, results are now based on the post-rise prices. Good for all but existing Scottish Power customers who should compare using Kilowatt hours used, not cost, as sites now inaccurately assume the past bill was accrued at post-rise prices, so it thinks you have used less than you have.

Should I call my existing provider to fix?

No. This is not about grabbing any fix; that could leave you locking-in at a high cost. It is about locking-in on the cheapest fix, so do a comparison.

The comparison showed me it will cost more to fix?

This is common if you are already on a cheap discount tariff. Prices are predicted, though not guaranteed, to rise 10-20 per cent, so if the additional cost of a fix is even more than that. It is likely to be best to stay put (unless there is yet another set of price rises afterwards). If the gap is less, balance savings now against a fix's price certainty.

Should I ditch my current fix to fix again?

Past fixes are likely to be much cheaper than current ones, so generally stick with them. Yet if you only have a short time left, the risk of waiting is that today's cheapest fixes will be replaced by costlier versions, so balance the cost of waiting against the £50-£80 exit penalty.

How long should I fix for?

Most fixes are 18 months, but longer ones at higher rates exist. While over the very long term, five-20 years, energy prices are likely to keep rising, market fluctuations can see prices drop over a shorter cycle. So prices could drop again in a year (or rise again).

So this is about your attitude to risk. If price certainty is more important than trying to play deals for the very cheapest prices, fix long.

I'm moving house - what happens to my fix?

Many fixed deals can be ported to your new house, though always check. If you move to a different region remember that different rates may apply.

I have a prepayment meter - can I get a fix?

Sadly not, as there is far less competition, which is out of order in my view. See if you can switch to a credit meter. If not, it is possible to switch prepayment providers, both Uswitch and Energyhelpline provide comparisons to see if you can save.

However it may be worth waiting until the rest of the big six energy providers have announced their price moves before comparing, so there is a level playing field when you do.