場合は【ばあいは】

場合は means "if", "in the event that": it sets up a situation that may or may not arise, and the rest of the sentence says what to do or what happens then. 場合 is a noun, so it follows the plain form of a verb or an い-adjective, a な-adjective with な, or a noun with の.

Instructions, rules, notices and manuals are full of it. In conversation the usual "if" is たら: ぱすわあどパスワードをわすれたら忘れたら.

Dictionary form or た-form

Before 場合は, the tense of the verb places the instruction in time. With the dictionary form, you act before the event; with the た-form, after it has happened.

Common mistake

場合は is for a contingency, something that might not happen. For a point that is sure to come, use とき or たら.

• × 夏休みになった場合は、旅行します → 夏休みになったら、旅行します
• × 大人になる場合は → 大人になったら

Usage notes

These go beyond "in the event that".

場合には and 場合も

ばあい場合には is a firmer version of 場合は and appears in contracts and regulations. ばあい場合も adds a case: "in some cases, also".

Person + の場合は

After a person, it means "in my case", "as for him".