Should Purchasing Department Be Capitalized?

When using the word 'department' (or 'group', 'committee', and the like) as part of a recognized name it would be capitalized: Bill recently joined the Advertising Department. If using 'department' not as part of a specific name it would be lower case: We had a party to welcome Bill to the department.

Should you capitalize department names?

Names of departments are capitalized only when using the full formal name, or when the department name is the proper name of a nationality, people, or race. Do not abbreviate to "dept." Capitalize as part of a full official name; lowercase otherwise.

Do you capitalize HR department?

Normally Human Resources is capitalized because it is the name of a department, just like you would capitalize Finance when referring to the department, but not when you were referring to the subject of finance.