Biannual = occurring twice a year.

• The committee published its biannual report as on 30th June and the next report is due by 31st December. (i.e. two reports in a year)

Annual = occurring once every year; covering the period of one year.

• The income tax is computed on the basis of one’s annual income.
• The Bank employees get reimbursements on the expenses on their annual physical check-up.
• It’s mandatory for companies to publish annual reports. (i.e. yearly once)

Biennial = occurring every two years. (i.e. once in two years)

• Biennial games
• Biennials are plants that live two years bearing flowers and fruit in the second year.