The coupon idea was raised by Education Vice-Minister Kitti Limsakul at an academic conference last week.
He suggested students be given coupons to redeem against tablet computer purchases, as a way to get around procurement and distribution problems in the government's One Tablet per Child scheme.
"The coupon, if approved, could widen the gap between students from well-to-do families and those from poorer backgrounds, since the former group can afford to buy tablets with higher specifications," Mr Chaturon said.
He suggested more affluent families could use the coupons as part-payments for more expensive models, while poorer families should use them to buy lower-spec models outright.
"The coupon would only benefit a small number of students and it would be hard to put into practice," he said.
"Delays in the distribution of tablets are difficult to solve because we have to comply with many regulations."
Anek Ratpiyapaporn, head of the Office of the Basic Education Commission's (Obec) Bureau of Technology for Teaching and Learning, supported the coupon idea, saying it would solve tablet procurement and distribution problems.
"This year, the tablets should have been delivered to students in June, but the first lot was delayed and the devices will now be distributed next month. We are already into the second term of this academic year," he said.
Mr Anek added that Obec has developed content for the tablets.
He said the content is compatible with Android and iOS devices, so there would be no problems if parents bought different brands with the vouchers.
Parent-Youth Network for Education Reform president Kamolpan Cheewapansri asked what the policy would be if parents who received the coupons chose not to buy tablets. She said the government should ensure more schools have internet access.
Arpakorn Samangyat, a mother of a Prathom 1 (Grade 1) student at La-orutis Demonstration School in Dusit district, said the tablet coupons should be given to underprivileged students in suburban schools.
"My son already has an iPad and other students in big schools also have iPads or similar devices which are superior to the tablets provided," she said. "So the government's tablets are of less use to these children [than pupils from families who cannot afford such devices]."
Chinese-made tablets were procured by the Information Communication and Technology Ministry last year and distributed to all Prathom 1 students nationwide.
In the 2013 academic year, the Education Ministry was responsible for tablet procurement through electronic auctions.