If you travel on your carrier on connection yes if it is the reverse no.
Ex:
You work for AA take a AF flight tkt from CDG to LHR to catch a AA flight arrive in the evening, overnight and take a morning AA flight . As long as you show the AF boarding which prove that you stayed less than 24h the agent can override the tax.
You fly on AA from the Usa to LHR to catch a BA flight to CDG even if you spend few hours you will have to pay the tax because the ticket have been previously issued by a third party and the BA agent have no control on that.