When you go through the form, you have about 20 minutes to complete each page. Don't use your normal 'Back' button to return to an earlier question, but use the 'Previous' button on the page you are on.
Questions marked * can't be left blank.
April 2019 changes
There is no discount available after 1 April 2019, but you can still apply for a one month discount if the property became empty and unfurnished before April 2019