CES asks how much effort a task took, usually as agreement with a statement. Use it after something the customer had to get done.
CES measures how hard something was, not how much someone liked it. It is the right question after a task with a clear finish line — opening an account, changing a plan, getting a refund — because effort predicts whether people come back better than satisfaction does.Phrase it as a statement to agree or disagree with, not a question. “Opening my account was easy” reads more naturally on an agreement scale than “How easy was opening your account?”.
Write the statement the respondent is agreeing or disagreeing with, and keep it to one task. A statement covering two steps produces an answer you cannot act on.
CES supports 5 or 7 points. Seven is the more common convention for agreement scales and gives respondents a finer choice; five is quicker to answer and easier to read on a phone. Pick one and keep it, since scores from different ranges are not comparable.