Income earned by a religious job holder need to file his income as a salary or other income from the 2018 FY, so if it's type of salary income, your organization should file by the 10th of March for 2018 FY.
If it's in other income, 80% of the income can be assumed as a necessary expenses.
Religious job holder included all kind of priest, pastor, minister in a church, monk, bonze in a temple, and missionary, evangelist, preacher and nun.
If it's an other income, you need to file it by the end of this coming May.
You need to file income other than following compensation; all of allowances for meals, housing, education, actual cost based compensation will be assumed as an expenses but not income.
It sounds like a very little income tax for this job holders since it's still controversial for taxation of this job holders in Korea.
Please send me an email to firstname.lastname@example.org for further questions.