Q. Do you recommend capitalizing offices such as the Office of the Attorney General and the Office of the City Clerk? These are formal names for administrative bodies, but they are shared names. In other words, every city has an Office of the City Clerk.
A. You can usually use initial caps for the name of a specific office but lowercase when referring to such an office as a generic term or concept. For example, we’d advise lowercase for your last sentence, where the use is clearly generic: “Every city has an office of the city clerk.”
The main reason for lowercase in that last sentence is that “Office of the City Clerk” may not reflect the wording used by each such office. Here are a few more examples:
Illinois’s Office of the Attorney General was established in 1818.
The Office of the City Clerk for Chicago can be found at City Hall.
Portugal’s Ministry of Finance (Ministério das Finanças) is headquartered in Lisbon.
but
In many countries, the treasury department is known as the ministry of finance.
Most states have an office of the attorney general.
The city clerk’s office is on the first floor.
See also CMOS 8.63–71.