I came across this example in a textbook:
Planen Sie auch Stau oder Ähnliches mit ein.
The verb is clearly "einplanen". The meaning of the sentence can be understood easily. However, I wonder why there is a "mit" there.
It is a particle/separable prefix that is written separately from the rest of the word.
So "mit einplanen" has two parts it can separate: "mit" and "ein". When the verb is "disassembled" in your sentence structure, you keep finding them in this order: Ich plane das mit ein.
.
For verbs for which permanent involvement/participation or union is expressed, it is written unseparated (in the sense of a spacing between them): mitbringen, mitmachen, mitwirken, mitwollen,
usw.
But this is by far not always clear and you could argue, a question of interpretation. Some allow both writings: mit berücksichtigen / mitberücksichtigen, mit unterzeichnen / mitunterzeichnen
.
Some that allow only separated writing are: mit ansehen, mit übernehmen.
So notably, "Hilf mir mit aufladen" and "Hilf mir mit dem Aufladen" don't use "mit" the same way.
Some examples for your understanding:
Ich muss das Dokument mitunterzeichnen / mit unterzeichnen.
Ich helfe, das Dokument mit zu unterzeichnen / mitzuunterzeichnen.
Wie unterzeichne ich das Dokument mit?
Sieh dir das mit an!
Ich will es mit ansehen.
"Mit" is stressed.
"Mit" in this case probably isn't a preposition, but a prefix to the verb "einplanen". "Miteinplanen" seems a bit unwieldy at first glance, but the similar verb "mitberücksichtigen" has entries at Duden and DWDS. Both mention "mit berücksichtigen" as "verwandte Form" and "Nebenform", respectively. I would understand "miteinplanen" or "mit einplanen" in a similar fashion. DWDS has a seperate entry for the prefix mit-, and Duden lists the similar prefix Mit- to use with nouns.
Mit can be used as a prefix on top of another prefix. It is separated with a space when the other prefix is separated as well, and it may be separated with a space otherwise.
The meaning is roughly also, as well.
miteinbeziehen
. Themit
andein
are in general separable, while thebe
is non-separable.