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Can vs. May–Not So Simple!

The correct places to use the words can and may are not as easily determined as we often imagine. I was reminded of the subtleties in my seminar with the Association of Legal Administrators last week, when an attendee questioned two of my uses. (Thanks, Jennifer! I appreciate your commitment to correctness.)

Here are the simple rules:

Can is for ability:
"Can you drive a car with a standard shift?"

May is for permission or possibility: 
"You may borrow my car next week." (Permission)
"I may arrive late." (Possibility)

But using the simple rules above, the choice between can and may may not be obvious in the sentences below. Which word would you choose?

  1. Can/May I have food served in the conference room?
  2. Yes, you can/may make arrangements with the onsite cafe.
  3. Professional guests can/may have their parking tickets validated.
  4. Please leave your phone number so that I can/may call you back.
  5. Please approve these specifications so we can/may process your order.
  6. You can/may review 440 lessons in the archives.

For the sentences above, does the meaning involve ability, possibility, or permission?

I would say each one involves ability. For example:

  1. Am I able to have food served in the conference room?
  2. Yes, you are able to make arrangements with the onsite cafe.
  3. Professional guests are able to have their parking tickets validated.

I do not see the sentences as communicating permission, but another person might view them that way:

  1. Am I permitted to have food served in the conference room?
  2. Yes, you are permitted to make arrangements with the onsite cafe.
  3. Professional guests are permitted to have their parking tickets validated.

My objection to may is that it may (possibility) be misunderstood. Do the sentences below indicate possibility or permission?

Professional guests may have their parking tickets validated.

Repeat visitors may receive a special discount.

I advise this approach:

If you intend "able to," use can.
If you mean "will possibly," use may.
If you intend "permitted to," use may.

I believe this approach will make the choice clear in nearly all instances, but I may be wrong. That is, I will possibly be wrong, and I am permitted to be wrong–sometimes. I certainly know I can be!


Posted by Lynn Gaertner Johnson
By Lynn Gaertner-Johnston

Lynn Gaertner-Johnston has helped thousands of employees and managers improve their business writing skills and confidence through her company, Syntax Training. In her corporate training career of more than 20 years, she has worked with executives, engineers, scientists, sales staff, and many other professionals, helping them get their messages across with clarity and tact.

A gifted teacher, Lynn has led writing classes at more than 100 companies and organizations such as MasterCard, Microsoft, Boeing, Nintendo, REI, AARP, Ledcor, and Kaiser Permanente. Near her home in Seattle, Washington, she has taught managerial communications in the MBA programs of the University of Washington and UW Bothell. She has created a communications course, Business Writing That Builds Relationships, and provides the curriculum at no cost to college instructors.

A recognized expert in business writing etiquette, Lynn has been quoted in "The Wall Street Journal," "The Atlantic," "Vanity Fair," and other media.

Lynn sharpened her business writing skills at the University of Notre Dame, where she earned a master's degree in communication, and at Bradley University, with a bachelor's degree in English. She grew up in suburban Chicago, Illinois.

23 comments on “Can vs. May–Not So Simple!”

  • Hi Lynn,
    This is great stuff! You likely can appreciate how tricky our language can be in that you get into trying to explain it to others during your workshops. Can and May are very common problem creators with my English students, and it’s usually a monster to try and explain. I liked your explanation, and I’ll be saving it to maybe make things easier on my students.

    One thing is explaining to a native english speaker, another thing is trying to do it with folks who are trying to learn it as a second language…the whole dynamic changes. Your post will be a very useful tool – thanks!

    Aaron in Mexico City

  • Aaron, I always like to hear your reactions and challenges. Let me know if you want me to write about any particular topics.

  • I’m so glad I happened across this post with the Google-search, “can vs. may”! Now that I grasp it, I’m sure I *can* use each properly; I *may* even be able to explain it to others! *May* I link to this post as a reference?

  • Thanks for the explanation. I have a 16 year old Godson that insists it’s “may you pass me the ketchup” and his cousin who says “may you give me the money to buy my own clothes”. Both are incorrect are they not?

  • Which is correct when answering the phone (business): (1) How CAN I help you? (2) How MAY I help you?

  • Hi, Betty. I prefer “How may I help you?” It seems to express the idea of “How am I permitted to help you?” along with the possibility of helping you.

    At the same time, I would not criticize “How can I help you?” meaning “How am I able to you?”

    I would just be happy to be helped!


  • Which is correct:
    ONLY Social Workers can join this group.
    ONLY Social Workers may join this group.

    (All the members of the group are Social Workers)

  • For possibility, an old journalism rule is to use “might” instead of “may”. Just discovered your posts and love it.

  • Thank you!! I am rewriting some bylaws for a non-profit that I belong to, and just hit the wall when I saw a “may” that didn’t feel quite right. Thank you for helping “climb” over that wall!! 😎

  • I am editing a document where the writer is consistently using “may”…ex:running the routine may generate errors. I keep changing it to “can” as far as I’m concerned, running the routine has the ability to generate errors. However, according to your post, there is the “possibility” to generate errors. Who’s correct? May didn’t sound right to me for this technical document, and there are a lot of “mays”.

  • My boss is waiting for a update from me to do somithing. Once I am done, shall I reply him

    Yes its completed. You may proceed now.


    Yes its completed. You can proceed now.

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