Page 1

☐ ☑ United States Securities and Exchange Commission Washington , D.C. 20549 Form 40 - F REGISTRATION STATEMENT PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934 OR ANNUAL REPORT PURSUANT TO SECTION 13 ( a ) OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 Commission File Number 001-15014 Sun Life Financial Inc. ( Exact name of Registrant as specified in its charter ) Canada ( Province or other jurisdiction of incorporation or organization ) 52411 ( Primary Standard Industrial Classification Code Number ( if applicable ) ) Not Applicable ( I.R.S. Employer Identification Number ( if applicable ) ) 1 York Street , 31st Floor , Toronto , Ontario , Canada M5J 0B6 ( 416 ) 979-9966 ( Address and telephone number of Registrant's principal executive offices ) Sun Life Assurance Company of Canada – U.S. Operations Holdings , Inc. One Sun Life Executive Park Wellesley Hills , Massachusetts 02481 ( 781 ) 237-6030 ( Name , address ( including zip code ) and telephone number ( including area code ) of agent for service in the United States )