President Rodrigo Duterte is flanked by lawmakers as he signs the Tax Reform Acceleration and Inclusion (TRAIN) law and the 2018 General Appropriations Act (GAA) at the Malacañang Palace on December 19, 2017. Rey Baniquet, Malacañang Photo

MANILA - Left-leaning opposition congressmen will bring President Rodrigo Duterte’s Tax Reform for Acceleration and Inclusion (TRAIN) law before the Supreme Court, Bayan Muna Rep. Carlos Isagani Zarate said Wednesday.

Duterte last week approved the law lowering personal income taxes while raising duties on fuel, cars, coal and sugar-sweetened drinks. Revenues will help fund the President's P8-trillion infrastructure program.

The 7-man Makabayan bloc's legal team is finalizing a case asking the high court to stop the implementation of the law, Zarate told DZMM.

"Busisiin mo iyung provision ng TRAIN. Mayroon ngang binigay na mga benepisyo sa kaliwang kamay, pero talagang nawawala rin dahil kinakain ng pagtaas ng mga presyo [ng bilihin], at pag-impose ng bagong taxes," he reasoned.

(Examine the provisions of TRAIN. You have benefits on one hand, but these are negated by the price hike of basic goods and the imposition of new taxes.)

TRAIN is also "legally infirm" because the House of Representatives ratified it despite the alleged lack of a quorum and voting, he added.

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Under the new law, the first P250,000 in annual income will be exempt from tax. The tax exemption cap on 13th month pay was also raised to P90,000 from P82,000.

Meanwhile, an excise tax will be charged on diesel at P2.50 per liter next year. This will be raised to P4.50 the following year and P6 in 2020. LPG will be taxed P1 per kilo in 2018 and will be increased to P2 pesos the following year and to P3 pesos in 2020.

The excise tax on regular and unleaded premium gasoline will be raised to P7 in 2018 from the current P4.35. This will be increased to P9 in 2019 and P10 in 2020.

Drinks with caloric and non-caloric sweeteners will be taxed P6 per liter while those using high fructose corn syrup will be charged P12 per liter.

For cars, the new rates will be 4 percent for vehicles whose manufacturer's price is up to P600,000, 10 percent for cars worth P600,000 to P1 million, 20 percent for cars worth P1 million to P4 million and 50 percent for vehicles worth over P4 million.