The Political Parties, Elections and Referendums Act 2000 (the 2000 Act) sets out the rules on what third party, or non-party campaigners, can spend on regulated campaign activity in the run-up to certain elections. Organisations able to register under the 2000 Act as third parties includes bodies such as charitable companies and charitable incorporated organisations. Part 2 of the Transparency of Lobbying, Non-Party Campaigning and Trade Union Administration Act 2014 (the 2014 Act) amended the 2000 Act. Amongst its provisions, part 2 of the 2014 Act reduced the overall maximum expenditure limit, widened the range of activities on which expenditure had to be accounted for and increased the threshold for registration. Additionally, it introduced two new concepts: a constituency spending limit, which applies to spending aimed at one or more particular constituencies, and targeted spending, which covers campaign activity aimed at influencing voters to vote for a political party or any of its candidates. This Lords Library briefing provides further information on the 2014 Act and a discussion of reports and commentary that have discussed the operation of the 2014 Act and the effect that it has had on third party campaigners.