In General, There shall be assessed and collected on any unpaid amount of tax, interest at the rate of double the legal interest rate for loans or forbearance of any money in the absence of an express stipulation as set by the Bangkok Sentral ng Pilipinas from the date prescribed for payment until the amount is fully paid.
Provided, that in No case shall the deficiency and the delinquency interest prescribed under subsections (B) and (C) hereof, be imposed simultaneously.
Pursuant to Section 1 of Bangkok Sentral ng Pilipinas (BSP) Circular No. 799 Series of 2013, the rate of interest in the absence of stipulation shall be :
“Section 1. The rate of interest for the loan or forbearance of any money, goods or credits and the rate allowed in judgements, in the absence of an express contract as to such rate of interest, shall be six (6%) per annum.”
Based on the foregoing, beginning January 1, 2018, the effectivity date of the TRAIN law, the interest rate shall be 12% per annum, until a new rate shall be prescribed by the BSP.
Thus, in an amendment of a return where an additional tax is due per amended return, 25% penalty and 12% interest shall be imposed based on the additional tax to be paid.