都度

1. Origins, structure, and basic meaning

• Structure: It is read つど. This word refers to each occasion on which something happens.
• Basic usage: It is used for recording expenses or checking questions on each occasion as they arise.
  • 費用が発生する都度、帳簿に日付と金額を記入する。

2. Common pitfalls and similar expressions

• Recurring occasions and register
  • 都度 is somewhat more formal than たび and suits procedures or instructions.
  • その都度 means on each occurrence of the event just mentioned.