Over a million homeowners will be hit by the mortgage rate rises announced over the past week. Karen Barrett (pictured, right), head of financial adviser search service Unbiased.co.uk, says not enough borrowers are preparing themselves for the hikes...

For some time now, there have been rumblings that the low interest rate environment we find ourselves in cannot last forever. When it comes to mortgages, the million dollar question has been: "When will they start to rise?"

Well, now we have the answer in a big way. But worryingly, our research shows too few borrowers are reviewing their mortgage, which could leave them paying far too much. So this is my call to action to all homeowners, not to rest on their laurels.

Despite the fact that the Bank of England base rate still remains at 0.5%, where it has been unchanged for three years, we are starting to see SVR rises from the likes of Halifax, Bank of Ireland and Clydesdale/Yorkshire banks.

RBS has also raised some offset rates for existing customers. This will have an effect on the mortgage payments of hundreds of thousands of customers.

These rate rises will actually bring some lenders' SVR rates back into line with those of other lenders (the average is currently around 4.8%) but if the cost of mortgage funding increases, it could open the gates to yet higher rates and further rises.

Halifax will increase its SVR from 3.5% to 3.99% in May. For a customer with a £150,000 repayment mortgage, their monthly payment will increase by around £40 a month.

This could have a significant impact on those who have been relying on the base rate remaining low (which it still is) and have not factored a mortgage rise into their overall financial planning.

The Bank of Ireland will hike its rates from 2.99% to 4.49% later this year, which will obviously have an even greater effect on its customers' monthly payments.

Many not acting

Our latest research found that almost half of homeowners with a mortgage (49%) have not reviewed their mortgage since March 2009, when the Bank of England base rate first fell to 0.5%.

There is no doubt consumers have benefited from the low base rate. But the latest activity from lenders shows it's always worth keeping an eye on what's available in the market to make sure you are making the most of the rates available.

Of those with fixed rate mortgages, only 49% said they'd reviewed their mortgage in the last three years. But the average rate they are paying is 4.63%, against the currently available best buy rates of 2.89% (two-year fix), 2.99% (three-year) or 3.49% (five-year).

Five-year fixes are popular at the moment, but there is a risk that when the rate ends borrowers could find themselves looking to remortgage at a time when rates have already risen.

Interestingly, we recently polled nearly 200 consumers asking if they would be interested in a 10-year rate, and 66% said they would be.

Check your rate

For those looking for peace of mind, going for a fixed rate can protect you from further rate rises and will also give you confidence in the long term that you can continue to afford your mortgage repayments.

For those who held tracker mortgages, 45% have reviewed their mortgage in the last three years and the average rate they are paying is 3.16%, against the current best buy of 2.59%.

There is definite value in reviewing your mortgage arrangements and to ensure you are getting the best deal.

Rates can usually be booked up to six months ahead of time so if you see a deal that you like and is right for you and your financial situation, you can secure it before your old rate runs out and before interest rates rise.

But before racing to remortgage, remember you will need to take into consideration redemption charges, mortgage arrangement fees and any other associated costs of remortgaging.

Recently, we have seen stricter lending criteria being put in place by lenders as well as stricter affordability controls, which means that some borrowers may not qualify for the best buy rates you see advertised.

Keep in mind, though, that the available mortgage deals come and go at a fast pace so make sure you shop around.

Given that no one can look into the future to know exactly when rates will rise, seeking the services of a whole-of-market mortgage adviser can give you unbiased advice, specific to your individual circumstances.

They can also advise on the best times to switch and the associated costs of redeeming your mortgage early.

Views expressed are not necessarily those of MoneySavingExpert.com.