The league tables are the industry's definitive guide to the UK's top PR firms and their revenues.
Agencies will need to enter online, as well as posting a copy of the form signed by their finance director and auditor or accountant. All entries are checked by the PRCA and Kingston Smith to ensure consistency.
The information will be used to compile a range of league tables, to be released throughout the year.
These will include the main Top 150 table and sector tables including consumer, healthcare, tech and public sector.
Agencies will need to submit their figures by Thursday 28 March. Click here to enter.