There are a number of reasons why a vote may be rejected. In the case of postal votes, the most common reason is that the signature and/or date of birth provided on the postal voting statement do not match the ones supplied on the original postal vote application form and any subsequent signature updates. If the postal voting statement is not accepted, then that voter’s ballot paper cannot be counted.
At the count, ballot papers are rejected if the intention of the voter is unclear, for example if a voter has marked their ballot paper incorrectly or voted for more candidates than they are entitled to.
There is guidance issued to Returning Officers to assist them in their decision-making, including examples of what should and should not be accepted, based on the legislation and case law.