The phrase is in common usage throughout English society, employed by headline writers in broadsheet gazettes and tabloids as well as colloquially and is also used in English speaking countries such as Australia.
In colloquial usage, 'taking the piss' is also used to refer to someone or something that makes a claim which is not in line with a recognised agreement e.g. an invoice that is double the quoted price with no explanation for the added charge could be said to 'take the piss', or likewise if something consistently misses a deadline.
"Take the mickey" is an abbreviated form of the Cockney rhyming slang "take the mickey bliss ("mickey" being slang for penis), meaning to "take the piss [out of someone]". The phrase has been noted since the 1930s.
An alternate, unverified, and unlikely theory of etymology is that "mickey" is a contraction of "micturition" (i.e., piss), "mickey" being a suitable alternative when in the company of those liable to be offended by "piss". Another theory is that "mickey bliss" was used as cockney rhyming slang for "piss", therefore explaining the origins of the phrase "taking the mickey".
It has also been suggested that "mickey" in this context is an ethnic slur for an Irish person (from the surname prefix Mc-), and to "take the mickey" originally meant to taunt the Irish and parody their accents.