Enforcement Rules of the Labor Standards Act Article 31

The pre-existing wage mentioned in Subparagraph 2 of Article 59 of the Act refers to the wage the worker received for the regular working hours in the day before the occurrence of occupational accident. Where the wage of the worker is calculated on a monthly basis, one day's wage shall be the amount equivalent to the wage the worker received for one month's regular working hours divided by thirty just one month immediately before the occurrence of occupational accident.If the amount calculated pursuant to the preceding paragraph for a worker with occupational disease falls short of the average wage, the average wage shall be used as the standard.
中文原文 勞動基準法施行細則第31條
本法第五十九條第二款所稱原領工資,係指該勞工遭遇職業災害前一日正常工作時間所得之工資。
其為計月者,以遭遇職業災害前最近一個月正常工作時間所得之工資除以三十所得之金額,為其一日之工資。
罹患職業病者依前項規定計算所得金額低於平均工資者,以平均工資為準。

English translation for reference only; the Chinese text prevails. Not legal advice.