Hi Ann,
ESA is actually an indefinite award. Although a 'prognosis' will be entered on the claimant's records to indicate when to expect reassessment, the reality is that it can be looked at again at any time once 3 months has passed since the last decision.
I'm afraid you need to get the ESA50 form completed and returned in the time stipulated, otherwise you run the risk of your claim being closed.
Don't forget to make full use of our ESA guide
ESA claims and appeals You might want to bookmark/favourite this on your web browser now so that you can find it easily in future. That will allow you to return with further questions/comments about your ESA without having to start a new topic each time (or us getting mixed up between your PIP and ESA). It helps us enormously when everything relating to the same claim are kept in one place - and I hope you will find it useful too