# Representation of the People Act 1983, Paragraph 20

Extent: E+W+S+N.I.

(1) Every ballot paper must contain an appropriate security marking (the official mark).
(2) The official mark shall be kept secret, and an interval of not less than seven years shall intervene between the use of the same official mark at elections for the same constituency.
(3) The returning officer may use a different official mark for different purposes at the same election.

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Source: https://www.legislation.gov.uk/ukpga/1983/2/schedule/1/paragraph/20 (the official version)
Page: https://openlegislation.uk/representation-of-the-people-act-1983/schedule-1/paragraph-20
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.