Post-Effective Amendment to Post-Effective Amendment by Investment Company (Form 485BXT)

As filed with the U.S. Securities and Exchange Commission on March 12, 2026

Securities Act File No. 033-31072

Investment Company Act File No. 811-05876

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

LORD ABBETT SERIES FUND, INC.

(Exact Name of Registrant as Specified in Charter)

30 Hudson Street, Jersey City, New Jersey 07302-4804
(Address of Principal Executive Office) (Zip Code)

Registrant's Telephone Number, including Area Code: (888) 522-2388

Brooke A. Fapohunda, Esq.

Vice President, Secretary and Chief Legal Officer
30 Hudson Street, Jersey City, New Jersey 07302-4804
(Name and Address of Agent for Service)

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

immediately upon filing pursuant to paragraph (b)

X on April 10, 2026 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:

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

EXPLANATORY NOTE

This Post-Effective Amendment No. 67 to the Registrant's Registration Statement on Form N-1A is being filed pursuant to paragraph (b)(1)(iii) of Rule 485 under the Securities Act of 1933, as amended (the "Securities Act"), solely for the purpose of designating April 10, 2026 as the new effective date of Post-Effective Amendment No. 65, which was filed on December 18, 2025 pursuant to paragraph (a) of Rule 485 under the Securities Act, relating to Lord Abbett Short Duration Income Portfolio. This Post-Effective Amendment No. 67 incorporates by reference the information relating to Lord Abbett Short Duration Income Portfolio contained in Parts A, B, and C of Post-Effective Amendment No. 65.

This filing relates solely to Lord Abbett Short Duration Income Portfolio. No information contained herein is intended to amend or supersede any prior filing relating to any other series of the Registrant.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Registration Statement under Rule 485(b) under the Securities Act of 1933, as amended, and has duly caused this Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Jersey City, and State of New Jersey on the 12th day of March, 2026.