= /Expenses:Transportation/ and not expr "has_tag(/NOTAX/)"
         Expenses:Tax                     0.2
         $account                        -0.2

2020-05-06 * Test
    Expenses:Transportation            200.00 EUR
    Assets:Bank                       -200.00 EUR

2020-05-06 * Test
    ; :NOTAX:
    Expenses:Transportation            300.00 EUR
    Assets:Bank                       -300.00 EUR

$ hledger -f- check

#test bal
#         -500.00 EUR  Assets:Bank
#          500.00 EUR  Expenses
#           40.00 EUR    Tax
#          460.00 EUR    Transportation
#--------------------
#                   0
#end test
#