Wells Fargo Municipal Capital Strategies Form 4 Nuveen AMT-Free Quality Municipal Income Fund / FARGO & COMPANY/MN WELLS ownership change

                                                                    EXHIBIT 99.1

                             JOINT FILING AGREEMENT

        Pursuant to and in accordance with the Securities Exchange Act of 1934,
as amended (the "Exchange Act"), and the rules and regulations thereunder, each
party hereto hereby agrees to the joint filing, on behalf of each of them, of
any filing required by such party under Section 13 or Section 16 of the Exchange
Act or any rule or regulation thereunder (including any amendment, restatement,
supplement, and/or exhibit thereto) with the Securities and Exchange Commission
(and, if such security is registered on a national securities exchange, also
with the exchange), and further agrees to the filing, furnishing, and/or
incorporation by reference of this agreement as an exhibit thereto. This
agreement shall remain in full force and effect until revoked by any party
hereto in a signed writing provided to each other party hereto, and then only
with respect to such revoking party.

        IN WITNESS WHEREOF, each party hereto, being duly authorized, has caused
this agreement to be executed and effective as of the date set forth below.

Date:   October 2, 2020                 WELLS FARGO & COMPANY


                                        By:   /s/ Patricia Arce
                                           ------------------------------------
                                           Name:  Patricia Arce
                                           Title: Designated Signer


                                        WELLS FARGO MUNICIPAL CAPITAL
                                        STRATEGIES, LLC


                                        By:   /s/ Alejandro Piekarewicz
                                           ------------------------------------
                                           Name:  Alejandro Piekarewicz
                                           Title: Vice President


                                        WELLS FARGO BANK, NATIONAL ASSOCIATION


                                        By:   /s/ Alejandro Piekarewicz
                                           ------------------------------------
                                           Name:  Alejandro Piekarewicz
                                           Title: Director