Watch more in iWantv or TFC.tv

MANILA – The "bureaucratic cost" of shifting to federalism, including increasing the number of senators, could cost P44 billion to P72 billion a year, according to a government think tank.

The government can raise new taxes or reduce spending to fund the changes, said Rosario Manasan, senior fellow at the Philippine Institute for Development Studies.

Manasan said federalism should take account the income disparity among regions. Three regions account for 62 percent of the economy: Metro Manila, Central Luzon and Calabarzon.

• More taxes for Juan under federal PH?
• Federalism 'anti-poor' due to double taxation: Davide

"The rest of the region has relatively small share in GDP. If you design it badly it can even widen the disparity," she said.

The shift to federalism was among President Rodrigo Duterte's campaign promises, saying it would help spread wealth and political power that had been concentrated in the capital for too long.

Both chambers of Congress are discussing a potential shift to federalism while a consultative commission created by the President is preparing its own recommendations.

• Duterte's charter change group begins work

• Draft constitution ready before Duterte SONA