I KNEW I should have done it. A couple of weeks ago, the thought crossed my mind that I might take the family to the United States this winter, taking advantage of the favourable exchange rate. Shortly after thought No 1, along came thought No 2: it might be prudent to buy a couple of thousand dollars while the going was so very good - after all, it was not likely that the pound would stay at dollars 2 for very long.

Of course I didn't do it, and now it's too late. As I write, the pound is standing at around dollars 1.70, which Americans in Britain and Britons in the US will all agree is nearer a realistic rate of exchange. Those dollars 2,000 are going to cost me about pounds 1,180 instead of pounds 1,000.

Many other skiers without the foresight to be currency speculators are naturally going to be hit in the same way, although not necessarily to the same extent (and not at all if going to Italy).

And what about the costs of holidays themselves? The pound has dropped 10 per cent against the schilling and the French franc since most brochure prices were set in the spring, and 15 per cent against the Swiss franc. Will packages be affected accordingly?

Yes and no. Many major operators - and practically all the big mainstream operators such as Thomson, Enterprise and Crystal - offer fixed prices. Many companies make no mention of it except deep in their booking conditions, as if it were now standard practice in the skiing trade. But it is not. The surcharge lives on.

Some companies will pass on increases resulting from 'governmental action' - a familiar clause in the surcharge business, but in current circumstances a rather interesting one. Does quitting the ERM count as governmental action?

'No,' says Paul Chase-Gardener of Bladon Lines, whose conditions include this provision. 'This is meant to cover such things as changes in VAT, or new levies on package holidays. We have forward cover for our foreign currency needs.' The brochure of the Meribel specialist, Snowtime, specifically mentions 'official revaluation or devaluation' as a form of government action. But the company's managing director, Don Kremer, says that the current position would not trigger a surcharge.

Other operators may apply surcharges if their costs go up for a wider range of reasons - for example, increased aircraft fuel costs (which depend on the dollar exchange rate) - or for any reason whatsoever.

If an operator threatens a surcharge, the next questions to be asked are: How much? And what choice do you have? Operators in the trade association ABTA have a standard set of terms they apply. Cost increases of more than 2 per cent are passed on, together with an amount to cover agent's commission.

If this means paying more than 10 per cent extra, you are entitled to cancel and to obtain a refund, losing nothing except your insurance premiums. (This in itself is a rip-off, of course, because your winter sports insurance - which is not cheap - becomes unnecessary if you cancel.) Other operators can apply whatever terms they wish - and one or two of those listed below do just that.

Since companies that levy (or threaten to levy) surcharges seem to survive from year to year, there are clearly some skiers who do not care about paying surcharges (or who do not know that they have a choice). Those who do care will want to note the list below.

This does not claim to be definitive, so if you worry about surcharges, check with the operator you intend to book with. Operators who provide for surcharges in the event of government action are not listed; if there were such action, is it likely that all uninvoiced holidays would be affected.

Any limits on the causes of surcharges are listed under the operator's name. 'Standard terms' means the ABTA terms spelt out above.

Among the operators that are not offering fixed prices are:

Austro Travel: Currency and fuel surcharges. Standard terms.

Le Ski: Fuel costs.

Lotus Supertravel: Currency, aircraft (sic), fuel, overflying charges, airport charges. Terms standard, except that surcharges may be levied up to 30 days before departure (ie, after you have paid in full).

Mark Warner: Currency, fuel, airport charges, overflying charges. Standard terms.

Meriski: Overflying and airport charges, fuel. Standard terms.

Powder Byrne: 'Owing to the continual fluctuations in currency exchange rates and fuel prices, PBI reserve the right to charge surcharges on the brochure prices. No refunds are made if sterling becomes stronger or flight costs decrease.' Sterling stuff from the Independent Young Entrepreneur of the Year 1988.

Ski Scott Dunn: Currency, fuel, overflying charges, airport charges, scheduled air fares. Standard terms.

Ski-Tal: Prices set at 1 May 1992, and subject to change 'in cases of devaluation and other significant increases in costs (by more than 5 per cent). Any resultant increase must be accepted by the client.' The company is inviting you to write a blank cheque.

Ski-Val: Prices set at 26 June 1992, when rates were higher than in March. Prices may have to be adjusted 'if exchange rates alter significantly'.

Snowtime: 'Subject to and in accordance with the booking conditions our prices are totally and unconditionally guaranteed for Snowtime's own accommodation holiday packages. The only exception to this guarantee is force majeure (without prejudice to the aforegoing expression, such as increases passed on to us by airlines) and government action such as the imposition of taxes, duties or levies or the official revaluation or devaluation of their currencies.'

YSE: Fuel. Standard terms.