Suppose that one player is a Scholar, an Architect, a Trader, a Seer or any other character that can build more than one district per turn. Suppose also that the Tax Collector is one of the character used in this game.
The rule-book states that:
When the Tax Collector is one of the characters in the game, players are charged a property tax for building districts. Immediately after a player builds a district, he places one gold from his stash on the Tax Collector’s character token. [...] If a player builds more than one district, he is charged the property tax for each district built. If a player has no gold remaining in his stash after building a district, he is not charged a tax. [...]
Suppose that our player has 10 golds and 2 district of cost 5. Can he build both districts and pay no gold to the Tax Collector or should he build only one district and pay one gold to the Tax Collector?
Or, in other words, can the building of more than one district be considered as a single action?
Note This question is concerning Citadels 2016 edition. However, a similar question could arise when playing the editions of 2000 and 2004 even if there isn't the Tax Collector character. So, if your answer isn't valid for all the three versions of the game, then please explicit the valid version(s).