The Anning family are among the millions of borrowers who immediately benefited from yesterday's one and a half percentage point Bank of England base-rate cut. Anyone who has a tracker, or is due to take out one, will notice a huge fall in repayments - £133 a month off an average loan.

However, cuts in the base rate are creating a nation of haves and have-nots, mortgage experts say. The haves are borrowers who picked up a great rate before the credit crunch; the have-nots are those who have had to take out a home loan in the past year and are paying hundreds of pounds a month more as a result - and there are more than a million of them.

Despite base-rate cuts, the cost of new deals is likely to stay high relative to pre-crunch levels, dragging more borrowers into the have-not category as they remortgage. Abbey and Woolwich increased their tracker rate deals before yesterday's rate cut, for example, while HSBC admitted that it would probably not pass on the full reduction. Ray Boulger, of the mortgage broker John Charcol, says: “Because of rate volatility there is a growing disparity between borrowers who took out a deal before last September and those applying for a loan now.”

Rate volatility has meant wildly different outgoings for families with identical financial circumstances: in August last year borrowers could pick up a two-year tracker rate from Cheltenham & Gloucester pegged at 1.01 percentage points below the base rate. After yesterday's cut, the happy crew on this deal are now paying interest of just 1.99 per cent. On a £150,000 loan, repayments are now £635: £156 cheaper than repayments for the neighbour down the road who took out today's best-buy tracker - a 3.99 per cent deal from First Direct, costing £791 on the same loan size.

Lisa and Jim Anning secured their deal in early September, before the collapse of Lehman Brothers sent lending into a spin. Their First Direct offset tracker charged 0.79 per cent above the base rate. They were expecting monthly repayments to rise. But, after the two recent base-rate cuts, their payments have fallen to less than they were on their previous home loan. “We are happy with the way it has worked out so far,” Lisa says. The Annings will save more than £1,000 this year. But will you benefit too?

What difference will a rate cut mean to my repayments?

If your lender does not pass on the cut, none whatsoever. A borrower on a tracker rate pegged at 0.5 per cent above base with a £150,000 loan will experience a £133 fall in repayments immediately. Borrowers with standard variable rate (SVR) deals will have to wait until their lender decides what to do. Those on fixed rates will not pay less, although lenders are now beginning to introduce cheaper fixes in response to falls in money markets.

Will house prices go up again?

A rate cut may help to restore confidence, but economists say that it typically takes around two years to filter through into economic performance. Property prices are not expected to recover until the end of 2009 at the earliest.

I am a first-time buyer - should I start to look now?

If your deposit is worth at least 10per cent, big falls in the price of some one and two-bedroom flats mean that now may be a good time to buy a home - as long as you can afford your repayments and you do not plan to move for a few years.

I took out a fixed-rate mortgage - was that a big mistake?

Even if your fixed rate means that you are paying more each month than people on trackers, your repayments will not rise should rates go back up again. The size of yesterday's cut may make any further falls unlikely.

I am on a standard variable rate. Will my monthly repayments come down?

Some lenders, such as C&G, have confirmed that they will pass on the full 1.5 per cent. Others are more reticent and have yet to say either way.

I am in negative equity and have a blemished credit record. Will lenders relax their rules?

Do not hold your breath. A base-rate cut has no bearing on the banks' attitude to risk. Lenders are still reluctant to offer loans to borrowers who do not have at least a 25per cent equity stake or deposit. Anyone who has had credit problems will still be viewed with suspicion and may be refused a loan.

My house has fallen in value - can I still remortgage?

Price falls mean that your loan-to-value (LTV) ratio - the proportion of the property's value that you are borrowing against - may have risen. This could mean that you are no longer eligible for the best rates. If your LTV is now above 90 per cent, you may be refused a new deal, forcing you to pay your lender's SVR.

I own a buy-to-let property and need to remortgage. What sort of deal can I get now?

The best deal is a 5.89 per cent two-year fixed rate from the Mortgage Works, worth up to 70 per cent of a property's value. Fees on buy-to-let deals are high, at about 2.5per cent of the loan.

I have a tracker pegged below the base rate. If the base rate falls to zero, what will happen to my loan?

It depends if your lender has a “collar” - a percentage below which it will not pass on cuts. HBOS has a collar of 3 per cent: Nationwide will not go below 2.75 per cent. However, C&G and Woolwich do not currently impose collars, so interest rates could technically fall to zero for tracker customers.

I am unhappy with my current deal. Can I change it?

If you are within the term of your deal, switching to another lender may mean that you have to pay an early repayment charge (ERC), often about 3 per cent of the loan. Do this only if the savings you make on the new deal will outweigh the cost of the ERC.

I need to remortgage. What are the best deals around?

Trackers are still best, according to brokers. Nationwide is offering a rate of 4.38per cent on its two-year tracker for LTVs up to 60 per cent of the property's value. First Direct's lifetime tracker charges 3.99 per cent up to 90 per cent, with a £399 fee.

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