Green’s Dictionary of Slang

tax n.

1. a stolen item, an act of theft.

[UK]Kendal Mercury 17 Apr. 6/1: Tom Wood was a cracksman [...] / Good at grabbing a reader, or freeing a prad, / Or lifting the tax from gents out on the pad.
OnLine Dict. of Playground Sl. 🌐 tax n. [...] A theft, stolen stuff.

2. (UK black) any form of charge, e.g. to a dance.

[UK](con. 1979–80) A. Wheatle Brixton Rock (2004) 138: There was another liquor-belly man [...] receiving the entry tax.
[Aus]Sydney Morn. Herald 18 Nov. 🌐 Fanum tax is a gag referring to YouTube creator Fanum, who ‘taxes’ people by stealing their food.

SE in slang uses

In compounds

tax-collector (n.)

a highwayman.

[UK]Lytton Paul Clifford II 97: The [...] ‘tax-collector,’ – for that was the designation by which Augustus thought proper to style himself and companions.
[UK]Farmer & Henley Sl. and Its Analogues.