Liberal Leader Justin Trudeau's proposal for a school supplies tax benefit for teachers goes "above and beyond" a broader employment benefit created by the Conservatives nearly a decade ago, his press secretary told CBC News.

Trudeau, a former teacher, promised a tax credit on up to $1,000 spent on out-of-pocket expenses starting this coming school year during a campaign stop at a school supplies producer in Newmarket, Ont. on Wednesday morning. The credit would be worth 15 per cent — or up to $150.

"I know very well as a teacher that sometimes you have out-of-pocket expenses to help enhance the activities in your classroom — everything from gold star stickers to times table posters. Unfortunately, those expenses aren't recognized by our federal tax system," he said.

The Conservative campaign called Trudeau's proposal redundant, claiming educators can already claim those costs under the Canada employment amount, introduced by the Conservatives in 2006.

The employment benefit "provides recognition for work-related expenses such as home computers, uniforms and supplies," with 15 per cent back on up to $1,127, according to the Canada Revenue Agency.

Trudeau's press secretary Zita Astravas told CBC News in an email that the benefit to teachers would go "above and beyond the employment credit that any employee in any field already receives."

The employment credit does not require receipts while the benefit proposed by Trudeau would require receipts.

Harper touts many Conservative tax credits

Conservative Leader Stephen Harper initially said the teacher benefit was "worth considering" when asked about it during his own campaign stop in Lancaster, Ont., shortly after Trudeau's announcement.

Harper also said that Trudeau appeared to be trying to "ape" the many Conservative tax credits that the Liberal Party has opposed in the past.

"It's an interesting switch for the Liberal Party," he said. "We brought in tax credits for students, for their bus passes, for their textbooks. We've brought in various plans to improve educational savings for Canadian parents — all things, which Justin Trudeau and the Liberal Party have opposed."

Harper announced his plan to introduce a tax credit for people who belong to service clubs, such as the Royal Canadian Legion, at a campaign event on Sunday.

NDP Leader Tom Mulcair also proposed a tax credit Wednesday that aims to bolster the sagging manufacturing sector by giving a break to businesses that invest in "innovation." He said it would save manufacturers $40 million annually by defraying costs of machinery, equipment and property to assist research and development in the manufacturing sector.