Who wrote today is the day by the barkays?

"Today Is the Day" was written by the American funk and soul band The Bar-Kays. The band, known for their energetic sound and contributions to the Stax Records label, released the song in the late 1970s. Their music often features a blend of funk, soul, and R&B influences. The Bar-Kays have had a significant impact on the genre, with several hits throughout their career.