If only the answer to that question were as simple. It depends on if you’re following the Oxford Handbook of Commercial Correspondence or the much less formal US conventions for letters.

So, depending on which side of the pond you fall, let’s look at how both British and Americans close their correspondence, such as thank you letters, business emails, and more.

British correspondence closings

Much more structured, the British letter closings have a purpose or a reason behind each that have lasted for generations. Back in 1928, Henry Watson Fowler wrote Modern English Usage as a companion to the Oxford English Dictionary. He humbly sought to present a unified and correct use of language, and most writers today refer to his works simply as "Fowler." Almost a century after his publication, Fowler remains the master of "The King’s English."

His guidance on properly closing letters is still in use today:

• Use "Yours faithfully" when writing to unknown persons on business matters
• Use "Yours truly" for slight acquaintances
• Use "Yours very truly" for ceremonious but cordial correspondence
• Use "Yours sincerely" when responding to invitations and friendly, but not intimate, letters

The Oxford Handbook of Commercial Correspondence follows Fowlers’ reasoning with more specifics. Their suggestions include:

• Use "Yours faithfully" when you begin a letter with "Dear Sir/Madam"
• Use "Yours sincerely" when you know the person’s name to whom you’re writing
• Use "Best wishes" when writing to someone you know well

Most Brits today avoid ending correspondence with old-fashioned closings like "We remain yours faithfully" or "Respectfully yours."

American correspondence closings

Much more relaxed, business correspondence in the US ends with "Yours truly" or "Sincerely yours." But even the Yanks have a hierarchy of correspondence closings depending on how chummy you are with the addressee.

Yours truly

A lot of American correspondence is closed this way because in the US, this closing doesn’t stand out. It’s the generic, plain vanilla way that ends a lot of business correspondence in the US.

Sincerely

This is a close second on generic endings for correspondence in the US. You’re safe to use either when writing a business letter in America.

Thanks again

Maybe because Americans aren’t quite as formal as Brits, they can use this closing. As long as you haven’t said "thanks" gratuitously in the body of your letter, closing by thanking them again is acceptable.

Regards

Whether you use "warm regards," "best regards," or simply "regards," this is an acceptable way to close correspondence in the US. Add "warm" or "best" when you want to seem a little less stiff. Almost like a polite smile.

Final thoughts

Brits use "Yours sincerely" while Americans write "Sincerely yours." British letter writers use "Yours faithfully" when they don’t know the name of the recipient, but Americans never use this closing. They’re more likely to close with "Yours truly."

Regardless if you’re writing the King’s English or the more relaxed Yankee version, when closing a letter to anyone, personal or business, capitalize only the first word.

• Yours faithfully,
• Yours sincerely,
• Sincerely yours,

In today’s digital global environment, people send a lot of correspondence via email. We’re curious. Does sending an email to the "Director of Human Resources" make you less formal than if you were sending a written letter? Let us know in the comments below if you stick to the formal rules for ending correspondence with "Yours sincerely" or "Yours faithfully."