The British administrators prior to independence introduced the khaki uniform for the Central Excise officials.
The uniform is described in the then Tobacco Excise Manual and the government of independent India continued it.
It is similar to the khaki uniform of police officials and was introduced by the British for discipline and uniformity as also to instill some fear in the minds of those who were not following the law.
It is dissimilar in respect of the shoulder badges, cap badge and logo or emblem so as to enable identification of the person as belonging to the police or to central excise.
Powers of search, seizure and arrest were also given to officers above a level, whereas in police it was up to a lower level.
The customs officers had white uniforms akin to those of naval officers but with differences in shoulder badges, cap badges, belt badges etc. to differentiate a customs officer from a naval officer.
Their winter uniform is different.
Currently in central excise the uniforms are prescribed for Sepoys, Drivers, Havaldars, Inspectors, Superintendents, Assistant Commissioners/Deputy Commissioners.
There is no uniform for ministerial staff (lower division clerks, upper division clerks, stenographers, assistants, Dos, OS, AO, CAO).
There is no uniform for the senior officers viz. Joint Commissioner, Additional Commissioner, Commissioner/ADG, Chief Commissioner/Director General etc.
For details please look in to the Tobacco Excise Manual IF A COPY IS AVAILABLE ANYWHERE, or any updated versions of the presently applicable general rules, regulations and orders relating to uniforms in the Central Excise, Customs, Service tax and Narcotics departments.