Recognize the situations in which to use the parenthesis when writing prose: explaining, translating, commenting, supplementing, listing, marking telephone area codes, citing literary works, making internal references and discussing sections of law or policy.
Replace parentheses with commas wherever possible to continue the flow of the sentence. This simple guideline will cut your use of parentheses by at least 50 percent. Preferred example: John, who is Joan's brother, drove us to the airport. Technically correct, but not preferred: John (who is Joan's brother) drove us to the airport.
Think of a parenthesis as part of a pair, except in some forms of a list or labels in a series. Surround your text with parentheses; don't leave one hanging alone. Exception: Listings might use 1) and 2) or a) and b) instead of (1) and (2) or (a) and (b).
Use parentheses when you want to include the equivalent Arabic numeral after the spelled-out version.
Indicate an equivalent entity with parenthetical punctuation. Examples: the Federal Bureau of Investigation (FBI) or the AMA (American Medical Association).
Copy the parentheses in telephone area codes, addresses, proper names/nicknames/titles and legal references precisely. Examples: (800) 555-1212; Roma, Italia (0801); Harry (Hal) Jones; 401 (k); SB 543, Section (b).
Embed literary citations by using parentheses. For example, use a numeral in parentheses to refer to a page number of a novel.
Place all punctuation for the sentence itself outside the parentheses and punctuation belonging to the parenthetical phrase within the parentheses. Example: The Chief Financial Officer shall oversee all fiscal operations (accounting, budgeting and governmental reporting), but she will not participate in strategic planning.