Short answers, pulled from the story.
George Harrison wrote Taxman after learning that high taxes placed The Beatles in the top tax bracket of the United Kingdom. A 95 per cent supertax introduced by Harold Wilson's Labour government meant the musicians paid over 90 per cent of their income to the Treasury.
The Beatles began recording Taxman on the 20th of April 1966 but left those initial results unused. The song's ending formed on the 21st of June when the section containing the guitar solo spliced onto the end replacing a formal conclusion after Harrison's final vocal line.
Paul McCartney handled bass duties while contributing distorted rhythm guitar and an Indian bit to the piece. Ringo Starr played drums and John Lennon provided backing vocals during the sessions.
Richard Goldstein wrote in The Village Voice that Revolver represented a revolutionary great leap forward for The Beatles with Taxman as the album's example of political cheek. Rolling Stone ranked the track at number 55 in 2010 describing it as a crucial link between earlier sounds and emerging psychedelia.
Harrison updated lyrics referencing John Major George Bush and Boris Yeltsin while including a new bridge ending with lines about taxing mats and overweight individuals. He first played Taxman live on his 1991 Japanese tour with Eric Clapton introducing it as a very old song written in 1873.