SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16 under

the Securities Exchange Act of 1934

For the month of ~~March~~September ~~2017~~2019

Commission File Number: 333-~~216137~~203859

TRANSCANADA TRUST

(Translation of Registrant’s Name into English)

450 –— 1st Street S.W., Calgary, Alberta, T2P 5H1, Canada (Address of Principal Executive Offices)

(Address of Principal Executive Offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F o

Form 40-F o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): o

The following documents are hereby filed with the Securities and Exchange Commission for the purpose of being and hereby are incorporated by reference into Registration Statement on Form F-10 (File No. 333-~~216137~~232968) of TransCanada PipeLines Limited and TransCanada Trust:

99.1. ~~Assignment~~ Underwriting ~~and Set-Off~~ Agreement, dated ~~as of March~~September 210, ~~2017~~2019, among TransCanada Trust, TransCanada PipeLines Limited, ~~TransCanada~~and ~~Corporation~~J.P. Morgan Securities LLC and ~~CST~~Citigroup ~~Trust~~Global ~~Company~~Markets Inc., as representatives of the several underwriters named in Schedule II thereof

~~2. Share Exchange Agreement, dated as of March~~EXHIBIT ~~2, 2017, among TransCanada Trust, TransCanada PipeLines Limited and CST Trust Company.~~INDEX

399. ~~TCPL~~1. Underwriting ~~Subordinated Note Purchase~~ Agreement, dated ~~March~~September 210, ~~2017~~2019, ~~between~~among TransCanada Trust, ~~and~~ TransCanada PipeLines Limited, and J.P. Morgan Securities LLC and Citigroup Global Markets Inc., as representatives of the several underwriters named in Schedule II thereof

4. Third Supplemental Indenture, dated as of March 2, 2017, between TransCanada PipeLines Limited, TransCanada Trust and CST Trust Company, as trustee, to the Trust Indenture, dated as of May 20, 2015 between TransCanada Trust and CST Trust Company, as trustee.

5. Third Supplemental Indenture, dated as of March 2, 2017, between TransCanada PipeLines Limited and Computershare Trust Company of Canada, as trustee, to the Subordinated Notes Trust Indenture, dated as of May 20, 2015, between TransCanada PipeLines Limited and Computershare Trust Company of Canada.

Signature

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	TRANSCANADA TRUST, by TRANSCANADA PIPELINES LIMITED, in its capacity as Administrative Agent
	TRANSCANADA TRUST, by TRANSCANADA PIPELINES LIMITED, in its capacity as
Date: March 2, 2017
	Administrative Agent
	By:	/s/ Christine R. Johnston
Date: September 11, 2019
		Name:	Christine R. Johnston
	By:	/s/ Christine R. Johnston
		Title:	Vice President, Law and Corporate Secretary
	Name:	Christine R. Johnston
	Title:	Vice-President, Law and Corporate Secretary

EXHIBIT INDEX

1. Assignment and Set-Off Agreement, dated as of March 2, 2017, among TransCanada Trust, TransCanada PipeLines Limited, TransCanada Corporation and CST Trust Company.

2. Share Exchange Agreement, dated as of March 2, 2017, among TransCanada Trust, TransCanada PipeLines Limited and CST Trust Company.

3. TCPL Subordinated Note Purchase Agreement, dated March 2, 2017, between TransCanada Trust and TransCanada PipeLines Limited.

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