[LETTERHEAD OF INVESCO CAPITAL MARKETS, INC.]
January 30, 2023
U.S. Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549
|Re:||Invesco Unit Trusts, Taxable Income Series 637
File No. 333-259440 CIK #0001686057
Ladies and Gentlemen:
In accordance with the provisions of Rule 497(j) under the Securities Act of 1933 (the "Securities Act") this letter serves to certify that the most recent post-effective amendment to the registration statement on Form S-6 for the above captioned Trust does not differ from that which would have been filed pursuant to Rule 497(b) of the Securities Act. The most recent post-effective amendment to the registration statement was filed electronically with the Commission on January 24, 2023.
Very truly yours,
/s/ Tara Baker
Vice President, Business
Operations and Quality Assurance
Invesco Capital Markets, Inc.