The official deadline is 28 June but entries will be accepted until Thursday 6 July, subject to a late fee.
The C&IT Awards are now in their sixth year, and the ceremony will take place at London Hilton on Park Lane on Friday 22 September.
Categories include UK Agency of the Year and Global Agency of the Year, which honours the best events agency with teams based in two or more countries.
Other categories include Internal Communications Event of the Year, Incentive Programme of the Year, UK Conference of the Year, Best use of Social Media/Technology and six sector categories including Automotive, Retail, and IT & Telecoms.
Last year’s C&IT Awards saw Rapport pick up four awards including the coveted Grand Prix for its ONE Astellas Live event.
More than 500 event industry professionals – a record attendance – saw Smyle Group crowned UK Agency of the Year and Avantgarde named Global Agency of the Year at the 2016 Awards.