勞工保險自實施老年年金以來，高薪低報問題嚴重，主因是勞工請領年金金額的公式當中，平均月投保薪資僅採計最高60個月的投保薪資，導致投保短期高薪即可獲得較高的老年年金計算基準，因此部分勞工與雇主會採取違法的高薪低報行為，來增加勞工收入或降低雇主的人事成本，而這會使勞保基金短收許多保險費，對勞保基金的永續運作造成重大不利的影響，但過去並未有學者針對此一重要議題進行估算。本文利用2016年「勞工投保薪資資料」及「受僱就業者每月收入資料」二項總體資料，來對上述違法的高薪低報行為對於勞保基金財務所造成的影響進行估算，研究結果顯示，勞工保險基金因違法高薪低報行為，每月短收約30億元保費，一年短收約360億元。此外，研究結果也顯示月薪資在2.5萬元至4萬元間的勞工，高薪低報的狀況是最嚴重的，他們會傾向用約2～2.5萬元附近的薪資投保。最後，薪資超過投保薪資上限的勞工，也有部分採用高薪低報行為。因此本文提出兩項政策建議，一是延長平均投保薪資採計期間，二是加強稽查及建立黑名單制度。

Since the implementation of labor insurance pension annuity, the problem of employers under-reporting employee salaries has become serious. The main reason is that the formula for determining the amount of annuity is based on the average of the highest 60 monthly insured salaries during the period of joining the insurance coverage. Some employers and employees take advantage of this formula by underreporting employee salaries in order to increase the income of employees or reduce the employer's costs. This illegal under-reporting problem has decreased the revenue of the labor insurance fund and has had a significant adverse impact on the sustainable operation of labor insurance. However, so far no scholars have estimated the financial impact that this under-reporting behavior has on labor insurance funds. This paper uses two datasets, ＂Labor Insurance Salary Information＂ and ＂Monthly Income of Employed Persons＂, to estimate the financial impact that under-reporting behavior has on the labor insurance fund. The results show that illegal under-reporting behavior decreases the revenue of the labor insurance fund by about 3 billion NTD per month, which is about 36 billion NTD per year. In addition, the results also show that the problem of under-reporting is the most serious for employees with monthly salaries between 25,000 NTD and 40,000 NTD. They all tend to report the insured salary at around 20,000~25,000 NTD. Finally, some of the employees with wages higher than the insured salary ceiling also under-report their salaries. Therefore, this paper proposes two policy recommendations: one is to extend the period of the insured salary used in the calculation of the amount of the annuity, and the other is to strengthen the audit and to set up a blacklisting system.