As an industry standard, 50% derating is necessary for MnO2 (standard) tantalum capacitors. The use of polymer technology allows for much less derating. The driving force behind derating capacitors is to achieve “acceptable” or little-noticed failures once the part is mounted and activated in the circuit. A 9PPM (parts per million) failure rate at 50% of the part’s rated voltage is required for the Tantalum-MnO2. This is matched by the 4PPM failure rate at 80% of rated voltage (20% derating) for the Tantalum-Polymer for voltages greater than 10VDC. The 4PPM level is matched or improved by a 2PPM failure rate for 90% of rated voltage (10% derating) for the Tantalum-Polymer with rated voltages of 10VDC or lower. Both of these are actually exceeded by the 0-PPM failure rate at 100% of rated voltage for the Aluminum-Polymer. There is no need to derate it.