It said the case involved “abuse of the international bonded warehouses system”.
Raids were carried out at 12 commercial and 17 domestic premises across south east England and the Midlands. Searches were also made at premises in Germany.
HMRC said it was suspected that alcohol was bought duty-free and claimed to be destined for EU markets but was smuggled back into the UK market without duty being paid.
Spokesman Bob Gaiger said: “More than 200 HMRC officers, supported by the police, took part in the operations.
“The operations spanned a number of counties and led to the arrest of 20 people. Our investigations are continuing.”?Arrests were made in Berkshire, Birmingham, Essex, Hertfordshire, Kent, London E6 and E17, Surrey and Sussex.