Corné Janse van Rensburg and the New Oxford Dictionary for Writers and Editors prefer one word. The online Oxford Dictionary gives it as one word but allows two words as an alternative.
And yet the Oxford Concise Colour Medical Dictionary (2010) and the Oxford South African Concise Dictionary (2010) both give it as two words, and the compound adjectival form before a noun is hyphenated, eg health-care commissioning.
So you have two choices:
- Either wed yourself to one authoritative word list and apply its usage consistently – in this case, either healthcare or health care.
- Or determine the most common usage in the document you are working on (where your author has been inconsistent) and go with that majority usage.
The advantage of the one-word option is that you don’t have to worry about hyphenating before a noun and leaving it as two words after a verb! One less editorial decision to make!
We editors should record these types of decision in a style sheet of our own for a particular client so that when they send us more texts to edit, we already have a record of previous decisions. It can also impress clients enormously if we show our professionalism by giving them our style sheet – especially if they themselves do not have a house style document or a style sheet of their own.