Once we used to read about the unfairness of gazumping, when a seller who had already accepted one buyer's offer then went on to accept a higher offer, depriving the first buyer of the property. Those days, other than in very exceptional circumstances, appear to have gone, and with declining prices it has become a buyers' market and a new phenomenon has taken its place – gazundering.

Gazundering happens where buyers demand a last minute price cut. This could happen shortly before exchange or even on the day of exchange. The seller is then left with the dilemma of potentially losing their buyer or even the property they wish to purchase if they don't accept this demand.

Gazundering is regarded by most as an unethical practice, but under English law it is legal because the terms of the sale can be changed until there has been an exchange of contracts.

There is always going to be a period of time between the price being agreed and exchange of contracts. The length of this period will depend on various factors including whether the buyer is obtaining a mortgage and whether there are any issues on the legal title to the property. If you are in a chain you can anticipate this period being much longer than the average period, which is said to be between six to eight weeks.

With the press almost daily full of stories of declining house prices across the UK, it is important to consider that no matter how good a purchaser may seem, they may attempt to gazunder.

In a declining market it is therefore worth considering the following, which may not stop gazundering, but may speed up an exchange of contracts:

Instruct your solicitor well in advance of marketing the property. Ask your solicitor to ensure that they have the title deeds to the property or to request them from your mortgage lender. Your solicitor will ask you to complete some standard forms that the buyer's solicitor will want to see.

• If your estate agent is producing the Home Information Pack (HIP) for you, ask whether a full local authority search will be included and ensure this is what is ordered. Many HIPs only include what is known as a personal search and these searches often do not have all the information contained in a full local authority search. Your buyer may otherwise have their solicitor carry out a full local authority search and this can delay the period between exchange and completion.
• If you are selling a leasehold property, make sure that your solicitors request service charge and insurance information from the managing agents as soon as possible as this sometimes takes a long time and can delay an exchange of contracts.
• If works have been done to your property or the search in your HIP reveals planning permissions and building regulation consents make sure your solicitor has copies or obtains these from the local authority. These are sometimes available online, but often are not. The buyer's solicitor will want to see copies before an exchange of contracts.
• Be realistic and discuss the price being offered by the buyer with your estate agent. If an offer price seems too good to be true in the current market, then it may well turn out that the buyer used this as a way of securing the property, but intends to drop the offer price – or gazunder - by between say 5% and 20% prior to an exchange of contracts.
• Be prepared. Consider what you would do if the buyer dropped the offer price between 5% and 20% shortly before or even on the day when you were supposed to exchange contracts. Would you be prepared to walk away? Some people might be prepared to do this or consider whether you will in fact be happy to accept the reduced price. You may be faced with a difficult decision if you intend to buy a property yourself of whether you should then gazunder on the property you are purchasing and continue the cycle.

Saskia Arthur is a partner at law firm Boodle Hatfield specialising in high value residential property. She can be reached via email: sarthur@boodlehatfield.com