まだ～ていません

まだ～ていません says something hasn't happened yet but is expected to. The verb goes in the て-form, followed by いません, and まだ comes before it.

Not the past negative

English says "haven't eaten", and that pulls learners towards たべませんでした食べませんでした. The past negative closes the matter: you didn't eat, and that time is over. 〜ていません says the not-eating is still the case now.

• × まだ食べませんでした → まだ食べていません

まだ with a plain negative, まだたべません食べません, is a different sentence again: "I'm not going to eat yet."

Answering a もう question

A question with もう ("already") gets まだ～ていません as its "no". The short answer is まだです.

Casual forms

Among friends, いません becomes いない, and the い of いない usually drops out in speech.