I had a boss a few years ago who sent me a Slack message that read, verbatim: “Per my last email, kindly adjourn to the conference room.”
We were a five-person startup. Nobody was wearing a suit. It felt like I was being summoned by the Queen.
That’s the moment I realized that a lot of people have absolutely no idea when to use formal language and when to just talk like a normal human being. They default to “formal” because they think it makes them sound more professional. It usually just makes them sound like a robot.
But on the flip side, you can’t just waltz into a serious legal or corporate situation throwing around emojis and slang. There is absolutely a time and a place for both. Here is the dead-simple breakdown of when to use which.
When to Go Formal
Formal doesn’t mean using big, fancy words just to sound smart. It means following traditional structure, leaving out personal fluff, and keeping a strict boundary between you and the reader. You use this when the stakes are high or when you don’t actually know the person.
Send a formal letter if:
- You are dealing with a government agency. Senators, the IRS, local city councils, passport offices. They still operate like it’s 1985. Give them formal formatting (dates, addresses at the top, formal closing).
- It’s a legal or serious medical matter. Disputing a bill, outlining an agreement, communicating with a hospital billing department. You want a paper trail that sounds serious.
- You are writing to someone you’ve never met. If you are cold-emailing a CEO or writing to a company for the first time, lean formal. You can always loosen up in the second email.
- You are writing a cover letter. Yes, even in 2024. Hiring managers still expect a certain level of traditional structure here.
A quick formal check: If you wouldn’t walk into the room and say “Hey guys,” you probably shouldn’t start your letter that way either.
When to Go Casual
Casual doesn’t mean unprofessional. It means conversational. You are writing the way you would speak if you were having a meeting over a cup of coffee rather than across a massive boardroom table.
Send a casual letter if:
- You are emailing a colleague. Even if you are asking them to do work, you don’t need to write “I am writing to request your assistance.” Just write, “Hey, do you have a minute to look at this draft?”
- You are following up with a warm lead. If you’ve already had a good conversation with a client and you’re just sending over the invoice or next steps, drop the stiff language. “Here’s what we talked about” works perfectly.
- You are thanking someone internally. A quick email to your team or a note to your manager about a successful project should sound human, not scripted.
- You are writing to a modern startup or creative agency. A lot of younger companies actively reject corporate speak. If you send them a letter starting with “To Whom It May Concern,” they might toss it out just on principle.
The Danger Zone: Mixing Them Up
Where people get into trouble is the middle ground.
Sending a highly casual email to a judge? You’re going to have a bad time. Sending a hyper-formal, three-paragraph email to your coworker asking if they want to grab lunch? They’re going to think you’re having a stroke.
The biggest trap I see is people trying to sound “smart” in casual situations. They use words like pertaining to instead of about, or utilize instead of use. It doesn’t make you sound more professional; it just makes the letter harder to read.
When in Doubt, Start Formal
If you are staring at your screen wondering which way to go, err on the side of formal. It is much easier to warm up a formal relationship in your second or third email than it is to recover from sending “What’s up?” to a bank executive.
And if the formatting is what’s holding you up—trying to remember where the date goes, how to space the addresses, whether to use “Sincerely” or “Best”—that’s the stuff that keeps people staring at a blank page for an hour. We built Instant Letter Pro to handle all of that for you. You just pick the tone, type your message, and we make sure it looks perfect.