As filed with the Securities and Exchange Commission on April 20, 2018.

Registration Nos. 2-99356

811-04367

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	☒
Pre-Effective Amendment No.	☐
Post-Effective Amendment No. 321	☒
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	☒
Amendment No. 325	☒

(Check Appropriate Box or Boxes)

COLUMBIA FUNDS SERIES TRUST I

(Exact Name of Registrant as Specified in Charter)

225 Franklin Street, Boston, Massachusetts 02110

(Address of Principal Executive Officers) (Zip Code)

Registrant’s Telephone Number, Including Area Code: (800) 345-6611

Christopher O. Petersen, Esq.

c/o Columbia Management Investment Advisers, LLC

225 Franklin Street

Boston, Massachusetts 02110

(Name and Address of Agent for Service)

Approximate Date of Proposed Public Offering:

It is proposed that this filing will become effective (check appropriate box)

☐ Immediately upon filing pursuant to paragraph (b)

☒ On April 25, 2018 pursuant to paragraph (b)

☐ 60 days after filing pursuant to paragraph (a)(1)

☐ On (date) pursuant to paragraph (a)(1)

☐ 75 days after filing pursuant to paragraph (a)(2)

☐ On (date) pursuant to paragraph (a)(2) of rule 485

If appropriate, check the following box:

☒ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

This Post-Effective Amendment relates solely to the Registrant’s Multi-Manager International Equity Strategies Fund series. Information contained in the Registrant’s Registration Statement relating to any other series of the Registrant is neither amended nor superseded hereby.

Explanatory Note

This Post-Effective Amendment No. 321 to the Registrant’s Registration Statement on Form N-1A is being filed pursuant to paragraph (b)(1)(iii) of Rule 485 of the Securities Act of 1933, as amended (the “1933 Act”), solely for the purpose of delaying, until April 25, 2018, the effectiveness of the registration statement for Multi-Manager International Equity Strategies Fund, filed in Post-Effective Amendment No. 315 filed on February 1, 2018, pursuant to paragraph (a) of Rule 485 of the 1933 Act. No other series of the Registrant is affected by the filing. Parts A, B, and C of Registrant’s Post-Effective Amendment No. 315, filed on February 1, 2018, are incorporated by reference.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant, COLUMBIA FUNDS SERIES TRUST I, certifies that it meets all the requirements for effectiveness of this Amendment to its Registration Statement under Rule 485(b) under the Securities Act of 1933 and has duly caused this Amendment to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Minneapolis, and the State of Minnesota on the 20th day of April, 2018.

COLUMBIA FUNDS SERIES TRUST I
By:	/s/ Christopher O. Petersen
	Christopher O. Petersen
	President

Pursuant to the requirements of the Securities Act of 1933, this Amendment to the Registration Statement has been signed below by the following persons in the capacities indicated on the 20th day of April, 2018.

Signature	Capacity	Signature	Capacity
/s/ Christopher O. Petersen	President	/s/ John J. Neuhauser*	Trustee
Christopher O. Petersen	(Principal Executive Officer)	John J. Neuhauser
/s/ Michael G. Clarke*	Chief Financial Officer	/s/ Patrick J. Simpson*	Trustee
Michael G. Clarke	(Principal Financial Officer)	Patrick J. Simpson
	Chief Accounting Officer
	(Principal Accounting Officer)
/s/ Douglas A. Hacker*	Chair of the Board	/s/ William F. Truscott*	Trustee
Douglas A. Hacker		William F. Truscott
/s/ Janet L. Carrig*	Trustee	/s/ Anne-Lee Verville*	Trustee
Janet L. Carrig		Anne-Lee Verville
/s/ Nancy T. Lukitsh*	Trustee
Nancy T. Lukitsh
/s/ David M. Moffett*	Trustee
David M. Moffett

*	By:	/s/ Joseph D’Alessandro
	Name:	Joseph D’Alessandro**
		Attorney-in-fact

** Executed by Joseph D’Alessandro on behalf of Michael G. Clarke pursuant to a Power of Attorney, dated May 23, 2016 and incorporated by reference to Post-Effective Amendment No. 261 to Registration Statement No. 2-99356 of the Registrant on Form N-1A (Exhibit (q)(3)), filed with the Commission on May 27, 2016, and on behalf of each of the Trustees pursuant to a Trustees Power of Attorney, dated January 1, 2018, and incorporated by reference to Post-Effective Amendment No. 315 to Registration Statement No. 2-99356 of the Registrant on Form N-1A (Exhibit (q)(1)), filed with the Commission on February 1, 2018.