Tày is the major Tai language of Vietnam, spoken by more than a million Tày people in Northeastern Vietnam. It was formerly known as Thổ, a name now shared with the Cuối language.

Tày is also spoken by emigrants in the Central highlands region of Vietnam (such as in Lam Dong Province).

There are also some Tày speakers in western countries. The region of Vietnam where Tày is spoken is bordered by China.

Tày linguistic varieties include the following:

Six tones are present in Cao Bẳng Tày:

The Tày people used to write their ritual texts and then songs with the logographic script, known as chữ Nôm Tày. The script is similar to sawndip and was created during the reign of Mạc dynasty, based on Chinese characters. Some of the characters, like Vietnamese Nôm, are borrowed directly from Han characters, while others are created locally from Chinese components.

The current Tày-Nùng orthography was created in 1961 on the basis of chữ Quốc ngữ, and then was approved by the government of Vietnam following the Decree 206-CP. Its alphabet contains 31 letters as follows:

Their pronunciation along with the multigraphs are listed in the tables below: