Thap Krit Tai () is a tambon (subdistrict) in Chum Saeng district, Nakhon Sawan province, Thailand.
Originally, Thap Krit Tai (lit "south Thap Krit") was a muban (village) in Thap Krit subdistrict, which consists of Thap Krit Nuea ("north Thap Krit), Thap Krit Klang ("central Thap Krit"), and Thap Krit Tai.
Later in the year 1997, when there is a lot more population, therefore officially split into a subdistrict.
Thap Krit Tai is a northern part of Nakhon Sawan province. It is located from downtown Chum Saeng and about from downtown Nakhon Sawan.
Nan river and Bueng Thap Krit Tai are important sources of water.
Neighbouring subdistricts are, clockwise from the north, Khok Mo and Thap Krit in its district, Kriangkrai and Bang Phra Luang in Mueang Nakhon Sawan district.
The entire area is under the administration of Subdistrict Administrative Organization (SAO) Thap Krit Tai.
The emblem of SAO Thap Krit Tai features paddy field and freshwater lake with mountains in the background inside the ears of rice frame.
The area also consists of eight administrative villages.
Thap Krit Tai is served by the Thap Krit and Khlong Pla Kot railway stations of the State Railway of Thailand (SRT), whose northern line runs through the area.