Accountants have a need to follow the rules. It creates order, and life is just simpler when everything goes the way it should.
While work never goes the way it should, accountants can at least rely on the established pen color hierarchy. The pen color hierarchy varies company to company, even office to office.
When followed at the office, it is important that this color code is never, ever broken. Having the pen color rule broken is akin to ghost ticking (tickmarking without having done the work).
Accountants will adopt a number of pen colors such as red, green, blue, black, etc. to represent different levels of seniority. At a company, an accountant could start out with a green pen. They would never be allowed by their peers to use any pen whose ink is not green until they get promoted in title. By following this rule consistently, it makes the seniority clear for who worked on a given task.
The pen color, not what is written, defines the accountant. Accountants (as sad as this sounds, it’s true) long for the day when they are allowed to use the next pen color.
New accountants who use the wrong color are harshly scolded and then learn the color hierarchy fast. On the other hand, interns who use the wrong pen color are considered amusing since interns are held to a different standard.
If you ever get an accountant a gift (and for some reason think a pen is an acceptable gift to give), you need to be aware of what color is the right pen color. Failure to pick the right color results in an awkward gift that an accountant may not be able to use for years. Even worse, the pen color may be considered beneath them.