The government's Tax Commission on Friday urged Prime Minister Taro Aso to clarify when the 5 percent consumption tax would be hiked to deal with the country's ballooning social security costs.

The tax panel, an advisory body to the prime minister but in reality less influential on policymaking than the ruling Liberal Democratic Party's tax panel, made the point clear in its recommendation before the government finalizes a midterm tax reform program by year's end.

"This commission strongly requests the government to draw up a midterm program that sufficiently reflects last year's recommendation contents, and clarifies the timing of implementing substantial tax reform," the commission said in its recommendation.