These two do almost opposite work. One takes something in, the other leaves it out. Which makes the mistake unusually jarring when it lands. "Everyone accept Maria" and "everyone except Maria" describe entirely different situations, and a reader has to stop and work out which one you meant.
A verb. To receive something offered, or to agree to something.
Usually a preposition meaning "not including." Occasionally a verb meaning to exclude.
Accept and except sound close in quick speech, especially at the start of a sentence, but they point in opposite directions. Accept means to take something in or agree to it: accept an offer, accept an apology, accept the terms. Except means leaving something out: everyone except Sam.
The first letters are a useful reminder. Accept starts with a, like agree. Except starts with ex, like exclude and exit, and that is exactly what it does to the thing after it.
Except can also be a verb meaning to exclude ("children are excepted from the fee"), but that is rare. In almost all everyday writing, if you are taking something, it is accept; if you are leaving something out, it is except.
Please except my apologies for the delay.
✓Please accept my apologies for the delay.
You are asking them to take your apology, so accept.
Everyone accept the finance team received the update.
✓Everyone except the finance team received the update.
The finance team is being left out, so except.
We cannot except payment by check.
✓We cannot accept payment by check.
Taking a form of payment is accept.
Quick way to remember
Try replacing the word with "take." If "take" fits — you take an offer, you accept an offer — use "accept." If the sentence means "but not," use "except," which shares its start with "exclude."
Is it "accept for" or "except for"?
Except for: "the room was empty except for a chair." There is no phrase "accept for" with that meaning.
How are they pronounced?
Accept is usually "ak-SEPT", and except is "ik-SEPT". The difference is the first vowel, which is why they blur together in fast speech.