Education authorities in Northern Ireland spent more than £22m on taxis over three years.
The Southern Education and Library Board was the biggest spender since 2006, according to figures revealed in the Assembly. It also covers one of the largest mainly rural areas with limited alternative transport links.
Taxis are primarily used for those with special education needs, the Department of Education said.
DUP MLA Thomas Buchanan obtained the information via a written answer at Stormont.
"It is worrying to note that in four out of the five board areas, expenditure on paying for taxis has increased in the 08/09 financial year," he said.
"£22.7m over three years seems an extremely high figure to be spent on taxis, particularly at a time when budgets are pressed and various government departments are trying their best to make valuable resources stretch."
The Southern Board spent £6.1m over three years from 2006, including £2.2m last year. Belfast spent £2.7m. The Northern Board spent £5.2m. The South Eastern Board spent £4.7m and the Western Board spent £3.8m.
Education Minister Caitriona Ruane said: "Taxis are primarily employed where statements of special education needs specify such provision, but may also be provided where the number of pupils on a route is so small that the provision of a bus cannot be justified and pupils have no alternative means of transport."
© Press Association