Beta readers can leave Amazon reviews if their review is honest, voluntary, and based on the book they actually read.

The safer approach is to ask beta readers only after the final version is published.

When It Makes Sense

A beta reader from your newsletter, reader group, or genre community may be a good early reviewer. They know the book and can describe the reading experience.

The review should reflect the finished book, not only an old draft.

When To Avoid It

Be careful with close friends, relatives, employees, contractors, or business partners. Those relationships can make the review look biased.

Also avoid making reviews a condition of beta reading.

Simple Request

Thank beta readers for their help. Then say that if they read the final book and want to leave an honest Amazon review, the link is available.

After that, leave the decision to them.