Improve the sentence: If you have been careful, you could have avoided the accident?

Have you had been

No correction is required

Had you have been

Had you been

The improved sentence would be: "Had you been careful, you could have avoided the accident."
This is a conditional sentence, and "had" is the correct auxiliary verb to use in the if-clause (instead of "have" or "had have"). The sentence is expressing a hypothetical situation, and "had you been" is the correct way to form the conditional perfect tense.