Formally / Formerly
Different meaningsFormally means officially or according to an established form; formerly means previously.
Formally
Use when
You mean officially, ceremonially or according to an established form or procedure.
Example
“The new unit was formally established on 1 April.”
Formerly
Use when
You mean previously or in the past.
Example
“The unit was formerly known as the Service Design Office.”
Quick check
formally known as when previously is meant, formerly approved when officially is meant, formal name confused with former name
Usage note