Asking for Permission: Should You Use “Can” or “May”?

One question that has popped up a few times on our Ask An Editor feature is whether to use “can” or “may” when you are asking for permission to do something. Does it matter which one you use? Are the words interchangeable?

Both “can” and “may” are auxiliary verbs, or “helping verbs”. On a practical level, this means they are used with a verb or verb phrase for whatever you are asking permission to do (e.g., go to the movies, take a day off from work, borrow someone’s pencil, etc.).

Traditional usage

Until about one hundred years ago, the meanings of “can” and “may” were more distinct. You might notice this if you are reading an older book or a newer novel or play that has a lot of “old-fashioned” dialogue.

Back then, “can” meant to be able/capable of doing something. “May” meant to have permission to do something. Children were often corrected if they used “can” to ask for permission.

What about now?

During the 20th century, the difference between “can” and “may” started to blur. Let’s look at an ordinary exchange between a teenager and his mom:

Jack: Can I drive the car?

Mom: Sure, just make sure you come home in time to finish your biology report.

In the above context, “can” is clearly being used to ask permission. Let’s see what happens when we write a different response from Mom:

Jack: Can I drive the car?

Mom: Yes, the guy from Sam’s Service Station replaced the dead battery this morning.

Here, we can tell from the context that “can” has taken on its traditional meaning. Jack isn’t sure if he is able to drive the car because of the dead battery.

Does this mean “can” and “may” are now interchangeable?

As we can see in the example about Jack and the car, it is now acceptable to use “can” to ask for permission and to ask if one is able to do something. However, “may” is never used to ask about ability or capability. “May I drive the car?” always means “Do I have permission to drive the car?” Thus, “can” and “may” are not interchangeable.

We also need to look at what happens when we use “can” and “may” in a declarative sentence rather than as a question.

Joy can turn in her book report on Wednesday.

Depending on the context, this could mean that Joy has permission to turn in her book report on Wednesday, or that she is able to turn in her book report on Wednesday. Basically, this is the same as when “can” is used to ask a question.

Joy may turn in her book report on Wednesday.

This sentence could mean that Joy has permission to turn in her book report on Wednesday. However, “may” is also sometimes used to indicate possibility. In the above sentence, it would mean that maybe Joy will turn in her book report on Wednesday, but maybe she won’t. We would need more context to know for sure.

Speaking of context, let’s look at some new versions of the above sentences about Joy’s book report:

Joy can turn in her book report on Wednesday because she is coming back to school that day. (Here, “can” means “is able to”.)

Mr. Khan said that Joy can turn in her book report on Wednesday instead of Tuesday. (In this sentence, Mr. Khan has given Joy permission to turn in her book report on Wednesday.)

Mr. Khan said that Joy may turn in her book report on Wednesday instead of Tuesday. (This is the same as the previous sentence except we are using “may” instead of “can”.)

Joy may turn in her book report on Wednesday if she finishes it while she is out of town with her family. (In this sentence, “may” means the same as “possibly”; it is not related to asking for permission.)

“May” is also sometimes used to convey a wish or hope. “May the force be with you!” from the Star Wars movies is one well-known example.

Formal and informal

If you need to ask for permission, how do you know whether to use “can” or “may”? If the context is informal, “can” is used more often than “may”. If you need to sound more formal or polite, then “may” is the better choice. You would also use “may” if you are writing a work of historical fiction.

If you would like one of our TextRanch editors to take a look at your writing and let you know if you are using “can” or “may” appropriately, please click the blue box below.