Learn Hardcore Japanese: tennyuutodoke wo teisyutusuru. - I submit a moving-in notification.

One small point: 届 can sometimes be associated with とどけ, as in a notice or notification, even though the single kanji 届 is often learned with the verb 届く（とどく） or 届ける（とどける）.

What exactly is 転入届?

転入届 is a noun meaning the official notification you file when you move into a new city, ward, town, or village in Japan.

It breaks down like this:

転入（てんにゅう） = moving in / transfer into a place
届（とどけ） = notice, notification, report

So 転入届 is not just any “document”; it specifically refers to the administrative moving-in notice used at a city office or ward office.

Why is the particle を used here?

を marks the direct object of the verb.

In this sentence:

転入届 is the thing being submitted
提出する is the action of submitting it

So:

転入届を提出する = submit the moving-in notice

This is a very standard pattern:

書類を提出する = submit documents
レポートを提出する = submit a report
申請書を提出する = submit an application form