How do you say "What do I need?" in Japanese?

Quick use

Use なにがひつようですか (nani ga hitsuyou desu ka) when you need to know what to prepare or show.

At a public office, this is useful when the staff mentions a procedure but you do not know which documents, ID, or forms are required.

Chunk or pattern

Use the full question first:

• なにがひつようですか = What do I need?

A related reusable pattern is:

• 〜がひつようですか = Do I need ...?

Examples:

• パスポートがひつようですか = Do I need my passport?
• ざいりゅうカードがひつようですか = Do I need my residence card?

Core words

• なに: what.
• ひつよう: necessary / needed.

Helper words and endings

• が: marks the thing that is needed.
• ですか: polite question ending.

Practical note

This is broad. If you specifically mean documents, どのしょるいがひつようですか (dono shorui ga hitsuyou desu ka) is clearer.