Take out a mortgage at a temptingly low interest rate, fixed for a certain time, and the chances are that for years afterwards you'll be locked in to a certain type of loan that costs you more than plenty of other offers around.

The money you save initially can all be blown by being forced to stick with a lender's standard variable rate for several years.

Borrowers today are growing increasingly aware of this type of "lock-in" clause attached to fixed, discounted or capped mortgages - and the penalties imposed for breaking the lock-ins.

This is why lock-ins have had such a bad press.

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Watch out for tie-ins and read the small print before signing anything, borrowers are warned. Banks and building societies - wicked as they are - will have you paying hundreds of pounds extra a year if you're not careful.

The Sunday Times has even been waging a campaign against these kind of deals.

And they are likely to come under scrutiny in the government's review of the industry.

But, as it happens, these deals could be about to change, for a variety of reasons.

Firstly, two lenders have dropped lock-ins altogether - a move which could prompt others to follow suit.

Secondly, some mortgage brokers are warning against banning them.

And thirdly, other observers believe that in the next few years, these special offers will disappear because lenders will not be able to afford them.

Lenders halt offers

The Nationwide has scrapped lock-in deals

Two of the UK's largest lenders - the Nationwide and Abbey National - have stopped offering cut-price mortgages with extended lock-in periods. The new discounted deal is slightly dearer than the old.

The Abbey even called on the government to ban them, saying they were not in customers' interests, but were only used to boost lenders' profits.

The Nationwide said four out of five borrowers preferred a loan without a tie-in. And there has been speculation that other lenders will either make them more attractive, or scrap them.

Undoubtedly, many people fail to understand the implications when they sign up to a cheap-rate home loan.

'Customers would lose'

But mortgage broker John Charcol says that's no reason to ban them - the answer is to spell out more clearly the cost. And it says a total ban would be against borrowers' interests in the long term.

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Managing director Ian Darby told BBC News Online: "Broadly speaking, we recommend either products which have no redemption penalties or only within the fixed-rate term. However, I don't think ultimately it would be in customers' interests to ban them.

"Anything that removes competition and differentials is reducing choice. It's in danger of getting out of hand. There's a great potential loser - the customer. It could only benefit lenders in the long run."

For example, a two-year fixed rate mortgage at 4%, followed by three years locked into the variable rate would still be cheaper than a current five-year fixed rate, according to John Charcol figures.

Also, a ban on lock-ins would mean no more cashbacks, said Mr Darby.

And deals which are cheap initially but dearer later are useful for people who are not earning much now, but are confident of high salaries later - trainee lawyers, for example.

"The issue is more about transparency and people understanding what they are letting themselves in for," he said.

So in their review, instead of outlawing fixed, discount and capped offers, the government should force lenders to express the potential penalties as pounds and pence, said Mr Darby. At the moment, they are given as percentages or a range of other jargon.

Levelling-out

There's also another school of thought: that with interest rates set to stay low as the UK prepares to join a single currency, banks and building societies will no longer be able to afford to subsidise discounted mortgages, and all home loans will level out at about the same rate.

Broker The Independent Mortgage Collection argues that the pool of funds used to fund them will dry up by 2002, so borrowers should take advantage now of any kind of discounts available.

At the same time, yet another type of mortgage has been born - the tracker loan, guaranteed never to be more than 1.75% above the base rate.

"They're a good idea if we're going to be in an environment of low interest rates and where lenders aren't passing on base rate reductions to customers," said Mr Darby.