Comma Before a Nonessential Adverbial Clause
The Comma
Rulebase Summary
Use a comma before a nonessential adverbial clause — one that follows the main clause and adds description or explanation but is not required for the sentence's core meaning. Words and phrases that always introduce nonessential clauses include: although, among which, even though, for, no matter what/who/which, none of which/whom, some of which/whom, though, and whereas. If the adverbial clause explains or elaborates (nonessential), a comma precedes it. If it states why (essential), no comma.
Examples
A. She left the firm in January although she had two years remaining on her contract.
A. She left the firm in January, although she had two years remaining on her contract.
Comma before nonessential 'although' clause.
A. He passed the inspection even though two violations had been noted earlier.
A. He passed the inspection, even though two violations had been noted earlier.
Nonessential clause adds info — comma before it.
Transcript Notes
The word 'whereas' is a subordinate conjunction — it is NOT a conjunctive adverb like 'however,' 'therefore,' or 'consequently.' Do not punctuate it with a semicolon before and a comma after. It follows standard adverb clause rules: comma after the clause when it begins the sentence ('Whereas corporate taxes are paid by the company, the partners pay personal taxes'), and a comma before it when it follows the main clause as a nonessential element.
Style Guide References (8)
Morson's
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