German for Experts Part 2 - writing verbs as one or two words
Many compound verbs are clear-cut and are spelt the same way as they were prior to the spelling reform: gemeinsam feiern, getrennt bezahlen remain separate. Verbs are written together as one word if the first part of the verb does not exist separately or cannot be clearly allocated to a word class or part of speech: abhandenkommen, übereinstimmen; heimkommen, kundtun.
Sein and participles
Compounds with sein, such as dabei sein or aus sein, are spelt as two words. Compound constructions are normally also separated if the first part is a participle: getrennt schreiben, gefangen nehmen.
Substantive + verb
Why is Rad fahren spelt as two words, whereas eislaufen is spelt as one? The corresponding rule stipulates that the verb must be spelt as two words if the first part is a full noun. If the noun is no longer used as such or cannot stand alone, the compound construction is spelt as one word.
Verb + verb
If the first part of a compound is a verb, the compound is usually spelt as two words: spazieren gehen, schreiben lernen. Compounds with bleiben or lassen in the second position can be written as one word if they have a figurative meaning: (auf dem Stuhl) sitzen bleiben (literal meaning: to remain seated (on the chair)), (in der Schule) sitzenbleiben (figurative meaning: to have to repeat a year (at school)).
Adjective + verb
A compound can be written as one word if the first part is a simple adjective but this is not possible if the compound is extended or if the comparative form of the adjective is used: kleinschneiden or klein schneiden but kleiner schneiden, ganz klein schneiden; reflexive forms, such as sich schön machen, are not written as one word either.
As with compounds that have a figurative meaning, compound verbs are written as one word if they have a new, separate meaning: den Verkehr lahmlegen.
Both are possible
One special feature of the new spelling is that in many cases it is possible to write compound verbs both as one word and as two words. Kennen lernen or kennenlernen? Both are correct.