"Maybe" (one word) = perhaps, possibly; "may be" (two words) = might be, could be.
Adverb: perhaps, possibly. Expresses uncertainty. Can come at the beginning or end of a sentence. Never directly followed by a verb.
Maybe I will go to the party if I finish work early.
She called to say she is running late. Maybe she is stuck in traffic.
"Are you coming to dinner?" "Maybe. I will let you know."
Modal verb "may" + verb "be". Expresses possibility as part of a compound verb phrase. Always followed by an adjective, noun, or participle.
This may be the most important decision of her career.
He may be late, but he will definitely arrive before the presentation starts.
The results may be ready by Thursday, depending on the lab schedule.
Common mistake
The easy test: try replacing with "perhaps". If it works, use one word: "maybe". "Perhaps I will go" = "Maybe I will go". If you cannot replace with "perhaps" (because it is part of a verb phrase), use two words: "may be". "It perhaps is true" sounds odd = "It may be true" (two words).
Trick to remember it
Replace with "perhaps": if it works, use MAYBE (one word). Replace the block with "might be": if it works, use MAY BE (two words). "Maybe" is never immediately followed by an adjective or participle as part of the predicate. "May be" is always followed by something (an adjective, noun, or participle).
Quick rule
Maybe (one word) = perhaps/possibly (adverb, replaceable by "perhaps"). May be (two words) = might be (modal verb phrase, replaceable by "might be").
Did you know?
The same pattern applies to: "maybe/may be", "everyday/every day", "already/all ready", "altogether/all together", "apart/a part", "sometime/some time". In every pair, the one-word version is an adjective or adverb, and the two-word version is a verb phrase or noun phrase. Once you learn the pattern, all of them become easy.
Exercise 1 · Pick the right one
_____ you should try talking to her directly instead of sending a message.
Exercise 2 · Pick the right one
The problem _____ more complex than we initially thought.
Exercise 3 · Form the word
Maybe (one word) = perhaps/possibly (adverb, replaceable by "perhaps"). May be (two words) = might be (modal verb phrase, replaceable by "might be").
The easy test: try replacing with "perhaps". If it works, use one word: "maybe". "Perhaps I will go" = "Maybe I will go". If you cannot replace with "perhaps" (because it is part of a verb phrase), use two words: "may be". "It perhaps is true" sounds odd = "It may be true" (two words).
Replace with "perhaps": if it works, use MAYBE (one word). Replace the block with "might be": if it works, use MAY BE (two words). "Maybe" is never immediately followed by an adjective or participle as part of the predicate. "May be" is always followed by something (an adjective, noun, or participle).
Bryan López
Founder of SpeakUP Academy