reinkommen
to come in
Colloquial for 'hereinkommen' (to come in); to enter a room or building.
Komm rein, die Tür ist offen!
Come in, the door is open!

to come in
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to come in
Colloquial for 'hereinkommen' (to come in); to enter a room or building.
Komm rein, die Tür ist offen!
Come in, the door is open!

The word is colloquial. The prefix 'rein-' is a short, informal form of 'herein-'. It expresses movement into a room or area.
Sollen wir schon reingehen oder noch draußen warten?
Should we go in already or wait outside a bit longer?
'Reinkommen' (to come in) is a separable verb. In a main clause, the prefix 'rein' goes at the end. In subordinate clauses and in the infinitive with 'zu', the verb stays together.
Er kam leise ins Zimmer rein.
He came quietly into the room.
The perfect tense of 'reinkommen' (to come in) is always formed with the auxiliary verb 'sein' because it describes movement or a change of state.
Bist du gestern gut nach Hause reingekommen?
Did you get home okay yesterday?
In this meaning, it is about abstract things becoming part of a selection or program. Typical contexts are exams, tests, topic lists, or competitions.
Ich habe Glück, mein schlechtestes Thema ist nicht in die Prüfung reingekommen.
I'm lucky, my worst topic didn't come up in the exam.
When it is about money, the subject of the sentence is often 'Geld' (money), 'Gehalt' (salary), or 'eine Zahlung' (a payment). It describes the moment when the money arrives in an account.
Ich kann das Auto erst kaufen, wenn das Geld von der Versicherung reinkommt.
I can only buy the car once the money from the insurance company comes in.
to occur / seem
'vorkommen' and 'reinkommen' can both be used when something plays a role in a test, a selection, or a plan. 'vorkommen' then means that a topic or task is included there or comes up. 'reinkommen' is more colloquial and emphasizes more that something is included in a selection. At school, for example, you would say: 'Das Thema kommt in der Prüfung vor.' (The topic comes up in the exam.) Colloquially, you can also say: 'Das Thema kommt in die Prüfung rein.' (The topic gets included in the exam.) Learners may confuse the words because both are formed with 'kommen'. 'vorkommen' sounds more neutral and fits more situations; 'reinkommen' is more casual and not suitable in every formal text.

Der Lehrer sagt, dass dieses Kapitel wahrscheinlich nicht in den Test reinkommt.
The teacher says that this chapter probably won't come up in the test.
In der Prüfung kommen auch Fragen zur Grammatik vor.
The exam also includes questions on grammar.