Free Writing Prospectus (to the

Filed pursuant to Rule 433

Preliminary Prospectus

Registration Statement No. 333-217624 and

Supplement dated May 7, 2019)

333-217624-01

Issuer:

Principal Financial Group, Inc. (the “Issuer”)

Expected Ratings

(Moody’s / S&P)*:

Baa1 (stable) / A- (stable)

Issue:

3.700% Senior Notes due 2029 (the “Notes”) fully and unconditionally guaranteed by Principal Financial Services, Inc. (the “Guarantor”)

Offering Size:

$500,000,000

Coupon:

3.700% per annum

Trade Date:

May 7, 2019

Settlement Date:

May 10, 2019 (T+3)**

Maturity Date:

May 15, 2029

US Benchmark Treasury:

UST 2.625% due February 15, 2029

US Benchmark Treasury Price:

101-17

US Benchmark Treasury Yield:

2.448%

Spread to US Benchmark Treasury:

130 basis points

Re-offer Yield:

3.748%

Price to Public (Issue Price):

99.602%

Net Proceeds to Issuer (Before Expenses):

$494,760,000

Interest Payment Dates:

Semi-annually on May 15 and November 15 of each year, commencing on November 15, 2019 (long first coupon)

Optional Redemption:

The Issuer may redeem the Notes, at its option, at any time and from time to time, in whole or in part, as set forth in the Preliminary Prospectus Supplement dated May 7, 2019 to the Prospectus dated May 3, 2017 (collectively, the “Prospectus”). If the Notes are redeemed prior to February 15, 2029 (the “Par Call Date”), the redemption price will be equal to the greater of:

(a) 100% of the principal amount of the Notes to be redeemed; or

(b) an amount equal to the sum of the present values of the remaining scheduled payments of principal and interest on the Notes to be redeemed that would be due if the Notes matured on the Par Call Date, not including any portion of the payments of interest accrued as of such redemption date, discounted to such redemption date on a semiannual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined in the Prospectus), plus 20 basis points, as calculated by an independent investment banker;

plus, in each case, accrued and unpaid interest on the Notes to be redeemed to, but excluding, the redemption date.

If the Notes are redeemed on or after the Par Call Date, the redemption price will be equal to 100% of the principal amount of the Notes to be redeemed plus accrued and unpaid interest on the Notes to be redeemed to, but excluding, the redemption date.

Special Mandatory Redemption:

The Issuer will be required to redeem the Notes, in whole, at a redemption price equal to 101% of the aggregate principal amount thereof, plus

accrued and unpaid interest on the Notes to, but excluding, the redemption date under the circumstances described in the Prospectus under the heading “Description of the Notes — Special Mandatory Redemption.”

Conflicts of Interest:

As described under the caption “Use of Proceeds” in the Prospectus, the Issuer intends to use the net proceeds from this offering, together with other available cash, to pay the Closing Consideration (as defined in the Prospectus).   Wells Fargo Bank, N.A., an affiliate of Wells Fargo Securities, LLC, is the Seller under the Purchase Agreement (each as defined in the Prospectus) and, accordingly, will receive the net proceeds from this offering. To the extent that any underwriter, together with its affiliates, receives more than 5% of the net proceeds of this offering, not including underwriting discounts and commissions, such underwriter would be considered to have a “conflict of interest” with respect to this offering pursuant to Financial Industry Regulatory Authority, Inc. (“FINRA”) Rule 5121. Pursuant to FINRA Rule 5121, the appointment of a qualified independent underwriter is not necessary in connection with this offering. No affected underwriter will confirm sales to any account over which it exercises discretionary authority without the prior written consent of the account holder.

CUSIP/ISIN:

74251V AR3/US74251VAR33

Joint Book-Running Managers:

Citigroup Global Markets Inc.

Goldman Sachs & Co. LLC

Merrill Lynch, Pierce, Fenner & Smith

Incorporated

BNP Paribas Securities Corp.

Morgan Stanley & Co. LLC

RBC Capital Markets, LLC

U.S. Bancorp Investments, Inc.

Co-Managers:

Barclays Capital Inc.

Credit Suisse Securities (USA) LLC

Deutsche Bank Securities Inc.

HSBC Securities (USA) Inc.

Wells Fargo Securities, LLC

Academy Securities, Inc.

Samuel A. Ramirez & Company, Inc.

Scotia Capital (USA) Inc.

The Williams Capital Group, L.P.