When a person who obtains eligibility as an insured person, the insurer determines the standard monthly remuneration amount with the amounts listed below as the monthly remuneration amount:
if the wages are determined on the basis of a monthly, weekly or other fixed period, the amount equivalent to thirty times the amount obtained by dividing the amount of the remuneration as of the day on which eligibility as an insured person is obtained by the total number of days in that period;
if the remuneration is determined on the basis of working days or hours, or in accordance with a piece rate or other contract price, the average of the amounts of remuneration received by persons engaged in similar work at the place of business for one month preceding the month in which eligibility as an insured person is obtained and who receive similar remuneration;
if it is difficult to calculate pursuant to the provisions of the preceding two items, the amount of remuneration received by a person engaged in similar work in the region for one month preceding the month in which eligibility as an insured person is obtained and who receives similar remuneration; or
in the case of receiving remuneration corresponding to two or more of the preceding three items, the total sum of the amounts calculated for each pursuant to the provisions of the preceding three items.
A standard monthly remuneration amount determined pursuant to the provisions of the preceding paragraph is the standard monthly remuneration amount of each month since the day on which the person obtained eligibility as an insured person until August in that year (August in the following year if the person obtained eligibility as an insured person between July 1 to December 31).