The EMU800 series was purchased in response to increasing passenger volume and electrification of branch lines, which diverted older commuter EMUs. At 296 cars, the order is the second-largest ever placed by TRA. The first two EMU800 trains were built by Nippon Sharyo, and the remaining 35 were built by the Taiwan Rolling Stock Company from 2013 to 2015. At the beginning there was a dispute for the brake system. After years of negotiation, TRA accepted the proposal and the EMU800 began to service.
Unlike previous commuter EMUs, the EMU800 features a fully streamlined nose. Its yellow-and-blue paint scheme has earned it the nickname "Smiling train" (微笑號) due to the way the stripe is painted on. The trainsets also have a top speed of 130 km/h (81 mph), compared to 110 km/h (68 mph) for all other commuter stock.
The EMU800 is also the first to have bicycle racks, installed in each of the end cars. Another feature new to the 800 is displays inside the cabin to broadcast messages. The EMU800 is meant to displace older locomotive-hauled trains and the older EMU500 on main line services.