1. In the event that a taxpayer has made overpayment of any tax as a result of mis-application of law or mis-calculation by him or herself, an application for refund of such overpaid tax supported by substantial documentation may be filed within five years from the date of payment thereof. Application for refund of such overpaid tax shall be denied if it is filed after the said five-year period. 
2. In the event that a taxpayer has made overpayment of any tax as a result of mis-application of tax law of mis-calculation by the tax collection authorities or other mistakes that can be attributed to relevant government agencies, the tax collection authorities shall refund the overpaid tax within two years from the date the mistake was found out, and the period of refundable overpayment of tax is not restricted to within five years from such date.