Co-pay vs copartnership: Prefix hyphenation in AmE

Solution 1:

The decision to hyphenate or not hyphenate is purely stylistic, thus the authority on the matter would be whatever style guide your publisher/editor/teacher uses.

There are numerous style guides, none of which is more correct than any other.

One commonly used style, called APA Style offers these guidelines:

General Principle 1

If a compound adjective can be misread, use a hyphen.

General Principle 2

In a temporary compound that is used as an adjective before a noun, use a hyphen if the term can be misread or if the term expresses a single thought (i.e., all words together modify the noun)...

Also use hyphens for

Compounds in which the base word is

• capitalized: pro-Freudian
• a number: post-1970
• an abbreviation: pre-UCS trial
• more than one word: non-achievement-oriented students

All "self-" compounds whether they are adjectives or nouns

• self-report
• self-esteem

https://www.apastyle.org/learn/faqs/when-use-hyphen