Free Writing Prospectus dated June 20, 2018

(to Prospectus dated December 13, 2017 and

Preliminary Prospectus Supplement dated June 20, 2018)

Filed pursuant to Rule 433

Registration Statement No. 333- 222022

$1,250,000,000 aggregate principal amount of 4.519% Fixed Rate/Floating Rate Senior Notes due 2024 (the “Fixed/Floating Rate Notes”).

4.519% per annum accruing from and including the Settlement Date to, but excluding, June 25, 2023 (the “Optional Redemption Date”) (the “Fixed Rate Period”).

Three-month U.S. dollar LIBOR plus 1.55% per annum, accruing from the Optional Redemption Date to, but excluding the Maturity Date (the “Floating Rate Period’).

The determination of LIBOR is subject to the provisions/circumstances set forth under “Description of the Senior Notes—Interest—LIBOR Discontinuation” in the prospectus supplement.

During the Fixed Rate Period, interest will be payable semi-annually in arrear on June 25 and December 25 of each year, commencing on December 25, 2018.

During the Floating Rate Period, interest will be payable quarterly in arrear on September 25, 2023, December 25, 2023, March 25, 2024 and the Maturity Date, commencing on September 25, 2023.

During the Fixed Rate Period 30/360 (Following, unadjusted)

During the Floating Rate Period, Actual/360 (Modified following)

Three-month U.S. dollar LIBOR, (Reuters LIBOR01), modified following, adjusted.

The determination of LIBOR is subject to the provisions/circumstances set forth under “Description of the Senior Notes—Interest— LIBOR Discontinuation” in the prospectus supplement.

100.000% of the principal amount of the Fixed/Floating

Rate Notes

The Fixed/Floating Rate Notes are not redeemable at the option of the holders at any time.

RBSG may redeem the Fixed/Floating Rate Notes at its sole discretion, in whole but not in part on the Optional Redemption Date at 100% of their principal amount plus accrued but unpaid interest to, but excluding, the date of redemption. In addition, RBSG may redeem the Fixed/Floating Rate Notes, in whole but not in part, at 100% of their principal amount plus accrued but unpaid interest to, but excluding, the date of redemption, upon the occurrence of certain tax or regulatory events as described in the prospectus supplement and the accompanying prospectus. See “Description of Debt Securities—Redemption,” “Description of the Senior Notes Loss—Absorption Disqualification Event Redemption” and “Description of the Senior Notes— Tax Redemption” in the prospectus supplement.

The Fixed/Floating Rate Notes contain very limited events of default provisions and the remedies available thereunder are limited, as described in the prospectus supplement under “Description of the Senior Notes—Events of Default and Defaults; Limitation of Remedies.”

Notwithstanding any other agreements, arrangements, or understandings between RBSG and any holder or beneficial owner of the Fixed/Floating Rate Notes, by its acquisition of Fixed/Floating Rate Notes, each holder and beneficial owner of the Fixed/Floating Rate Notes acknowledges, accepts, agrees to be bound by and consents to the exercise of any UK bail-in power by the relevant UK resolution authority which may result in (i) the reduction or cancellation of all, or a portion, of the principal amount of, or interest on, the Fixed/Floating Rate Notes; (ii) the conversion of all, or a portion, of the principal amount of, or interest on, the Fixed/Floating Rate Notes into ordinary shares or other securities or other obligations of RBSG or another person and/or (iii) the amendment or alteration of the maturity of the Fixed/Floating Rate Notes, or amendment of the amount of interest due on the Fixed/Floating Rate Notes, or the dates on which interest becomes payable, including by suspending payment for a temporary period; which UK bail-in power may be exercised by means of variation of the terms of the Fixed/Floating Rate Notes solely to give effect to the exercise by the relevant UK resolution authority of such UK bail-in power. Each holder and beneficial owner of the Fixed/Floating Rate Notes further acknowledges and agrees that the rights of the holders and/or beneficial owners under the Fixed/Floating Rate Notes are subject to, and will be varied, if necessary, solely to give effect to, the exercise of any UK bail-in power by the relevant UK resolution authority.

For these purposes, a “UK bail-in power” is any write-down, conversion, transfer, modification or suspension power existing from time to time under any laws, regulations, rules or requirements relating to the resolution of banks, banking group companies, credit institutions and/or investment firms incorporated in the United Kingdom in effect and applicable in the United Kingdom to RBSG or other members of the Group (as defined in the prospectus supplement), including but not limited to any such laws, regulations, rules or requirements which are implemented, adopted or enacted within the context of a European Union directive or regulation of the European Parliament and of the Council establishing a framework for the recovery and resolution of credit institutions and investment firms and/or within the context of a UK resolution regime under the Banking Act 2009, as the same has been or may be amended from time to time (whether pursuant to the Financial Services (Banking Reform) Act 2013 (the “Banking Reform Act 2013”), secondary legislation or otherwise, the “Banking Act”), pursuant to which any obligations of a bank, banking group company, credit institution or investment firm or any of its affiliates can be reduced, cancelled, modified, transferred and/or converted into shares or other securities or obligations of the obligor or any other person (or suspended for a temporary period) or pursuant to which any right in a contract governing such obligations may be deemed to have been exercised. A reference to the “relevant UK resolution authority” is to any authority with the ability to exercise a UK bail-in power.

NatWest Markets Securities Inc.

Merrill Lynch, Pierce, Fenner & Smith

Incorporated

Citigroup Global Markets Inc.

Goldman Sachs & Co. LLC

Wells Fargo Securities, LLC