Many of us have responded generously to the tsunami disaster in Asia, but only a few are making use of generous government tax reliefs here.

Charities appealing for donations are missing out on ?33m of extra cash according to the central body co-ordinating the UK's relief effort. The Disasters Emergency Committee, which represents 12 charities involved in the Indian Ocean region, says a total of about ?200m had been given or committed by Thursday, but only a small proportion of that was in the form of tax relief channelled through Gift Aid.

A committee spokesman says: ?Gift Aid will make up only 10 per cent of the final appeal total, judging by past experience, because people donating by phone have to be written to, to gain the tax relief.?

Banks have waived all commission charges on donations made from credit or debit cards to the committee appeal, according to the Association of Payments Clearing Services (Apacs). It says this is typical of such appeals. If a donation is made for the tsunami appeal to a charity directly from a bank account where a charge would normally be taken, the individual should tell the bank when the donation was made and the charge will be waived.

The low use of Gift Aid has, however, dashed hopes by the Charities Aid Foundation (CAF), which provides financial services to charities, that donors would use tax-efficient payment methods. The CAF says that in a typical year a third of donations are made using Gift Aid, which is worth ?2.7bn on top of the ?7bn contributed.

Cathy Pharoah, CAF director of research, says: ?I am hoping the tsunami appeal will catalyse the use of tax-efficient methods.? Gift Aid was launched in 1990 as a simpler alternative to covenants. For each ?1 given by a UK taxpayer using Gift Aid, charities receive an extra 28p from the Inland Revenue. The 28p is based on a gross roll-up of the 22 per cent basic rate of taxation. Higher-rate taxpayers can claim back the difference between basic rate and higher rate tax on their annual self-assessment form. This money can be given to the charity of choice or kept, according to the Inland Revenue.

The Revenue and government have done much to simplify Gift Aid, and the main requirement left for individuals donating is to remember which charities have benefited. The system is, however, designed to work for UK taxpayers only. UK service personnel posted overseas but donating to a UK charity can benefit from Gift Aid, as can non-UK domiciled individuals paying UK income tax.

For US passport holders, however, tax relief on Gift Aid donations claimed in the UK is clawed back by the US Internal Revenue Service, says the CAF. It recommends the use of the Southampton Row Trust, an intermediary it set up in 1999 to deal with the issue, to make the donation. Dominic Lawrance, a private client solicitor at law firm MacFarlanes, says that in a 2002 change to the Finance Act, people could carry this Gift Aid tax relief back one year in effect allowing individuals to offset a donation against their previous year's earnings, a move designed to help those retiring.

Lawrance adds that a change last year meant that people receiving a tax rebate from the Inland Revenue could also tick a box on their self-assessment form to give this money to charity. The only restriction now on the operation of Gift Aid by charities is that it is generally available only for straight donations and not for purchaes of goods or services from charities. The National Lottery is a charity, but you can't channel extra cash to it when you buy a ticket because you are buying a chance to win a prize.

Next year this rule may also affect museums and other charitable institutions that charge entrance fees to exhibitions.

Museums can use Gift Aid now to reclaim tax on tickets to special exhibitions, such as the National Gallery's recent Raphael show. The government has proposed that, from next year, the tax relief should be claimed only if visitors paid an extra 10 per cent for tickets. Lawrance says the most tax-efficient way to donate was to use the ?gifts of qualifying investments? rule. This allows shares and land to be given to charity. These so-called share aid and land aid schemes allow donors to avoid capital gains tax on any increase in value of these investments and write off the value of the land against their income tax.

Schemes such as www.sharegift.org/sharegift have been set up to facilitate the donation of usually small amounts of stock. The third main way of giving tax-efficiently is through the company payroll. These payments are made gross of tax, with the hope that workers will use this convenient system to give more generously.