Taxing religious groups will add 64.7 billion won ($57 million) to state coffers annually starting next year, a report said Monday.

The Moon Jae-in government has pledged to levy taxes on the clergy from 2018 onwards as part of its drive for equitable taxation, although people working for churches and temples have been exempted from paying income tax until now, as their work has been regarded as a spiritual service, not labor.

"We estimate the amount of taxes to be paid by employees of religious organizations next year to be around 64.7 billion won," Chung Chang-soo, head of the National Finance Institute, said in a report, noting 89 percent of religious employees currently do not pay taxes.