Nel marzo 2019, il parlamento britannico ha votato contro May per chiedere all'UE di ritardare la Brexit fino ad aprile, e successivamente a ottobre. Non avendo ottenuto l'approvazione del suo accordo, May si è dimessa da primo ministro a luglio ed è stata sostituita da [[Boris Johnson]]. Egli ha cercato di sostituire parti dell'accordo e ha promesso di lasciare l'UE entro la nuova scadenza. Il 17 ottobre 2019, il governo britannico e l'UE hanno concordato un accordo di ritiro riveduto, con nuovi accordi per l'Irlanda del Nord.<ref name="auto2">{{Cita web|url=https://ec.europa.eu/commission/sites/beta-political/files/revised_withdrawal_agreement_including_protocol_on_ireland_and_nothern_ireland.pdf|titolo=Revised Withdrawal Agreement|cognome=|nome=|sito=|editore=European Commission|data=17 ottobre 2019|accesso=17 ottobre 2019|urlarchivio=https://web.archive.org/web/20191017103006/https://ec.europa.eu/commission/sites/beta-political/files/revised_withdrawal_agreement_including_protocol_on_ireland_and_nothern_ireland.pdf|dataarchivio=17 ottobre 2019}}</ref><ref name="BBC News">{{Cita news|nome=|cognome=|url=https://www.bbc.com/news/uk-politics-50079385|titolo=New Brexit deal agreed, says Boris Johnson|editore=BBC News|data=17 ottobre 2019|accesso=17 ottobre 2019|urlarchivio=https://web.archive.org/web/20191213193556/https://www.bbc.com/news/uk-politics-50079385|dataarchivio=13 dicembre 2019}}</ref> Il Parlamento approvò l'accordo per un ulteriore controllo, ma rifiutò di passarlo in legge prima della scadenza del 31 ottobre e costrinse il governo (attraverso il "Benn Act") a chiedere un terzo ritardo sulla Brexit. Il 12 dicembre si sono quindi svolte le [[Elezioni generali nel Regno Unito del 2019|elezioni politiche anticipate]]. I conservatori hanno vinto una larga maggioranza in quelle elezioni, con Johnson che ha dichiarato che il Regno Unito avrebbe lasciato l'UE all'inizio del 2020.<ref>{{Cita web|url=https://www.msn.com/en-us/news/world/conservatives-headed-for-commanding-majority-in-uk-vote-brexit-will-happen/ar-AAK4vR4?ocid=spartanntp|titolo=Conservatives Win Commanding Majority in U.K. Vote: 'Brexit Will Happen'|cognome=Landler|nome=Mark|sito=[[The New York Times]]|editore=[[New York Times Company]]|data=12 dicembre 2019|accesso=12 dicembre 2019|urlarchivio=https://web.archive.org/web/20191213060550/https://www.msn.com/en-us/news/world/conservatives-headed-for-commanding-majority-in-uk-vote-brexit-will-happen/ar-AAK4vR4%3Focid%3Dspartanntp|dataarchivio=13 December 2019}}</ref> L'accordo di recesso è stato ratificato dal Regno Unito il 23 gennaio e dall'UE il 30 gennaio; è entrato in vigore il 31 gennaio.<ref name="auto4">{{Cita web|url=https://amp.theguardian.com/politics/2020/jan/24/sombre-eu-leaders-sign-brexit-withdrawal-agreement|titolo=Boris Johnson signs Brexit withdrawal agreement|cognome=Boffey|nome=Daniel|editore=The Guardian|data=24 gennaio 2020|accesso=24 gennaio 2020|urlarchivio=https://web.archive.org/web/20200124122448/https://amp.theguardian.com/politics/2020/jan/24/sombre-eu-leaders-sign-brexit-withdrawal-agreement|dataarchivio=24 gennaio 2020}}</ref><ref>{{Cita news|nome=Andrew|cognome=Sparrow|url=https://www.theguardian.com/politics/live/2020/jan/29/pmqs-boris-johnson-corbyn-warned-he-faces-first-commons-revolt-since-election-over-huawei-live-news|titolo=Brexit: MEPs approve withdrawal agreement after emotional debate and claims UK will return - live news|pubblicazione=The Guardian|data=30 gennaio 2020|accesso=30 gennaio 2020|urlarchivio=https://web.archive.org/web/20200129232319/https://www.theguardian.com/politics/live/2020/jan/29/pmqs-boris-johnson-corbyn-warned-he-faces-first-commons-revolt-since-election-over-huawei-live-news|dataarchivio=29 gennaio 2020}}</ref><ref>{{Cita news|url=https://www.bbc.co.uk/news/uk-politics-51333314|titolo=Brexit: UK leaves the European Union|editore=BBC News|data=31 gennaio 2020|accesso=1 febbraio 2020|urlarchivio=https://web.archive.org/web/20200131232236/https://www.bbc.co.uk/news/uk-politics-51333314|dataarchivio=31 gennaio 2020}}</ref>
Molti effetti della Brexit dipendono da quanto il Regno Unito sarà strettamente legato all'UE o dal fatto che il periodo di transizione si concluda senza un accordo ("Brexit senza accordo").<ref name="Edgington2">{{cite news|author=Tom Edgington|title=Brexit: What is the transition period?|publisher=BBC News|url=https://www.bbc.com/news/uk-politics-50838994|date=31 January 2020|access-date=1 February 2020|archive-url=https://web.archive.org/web/20200131215049/https://www.bbc.com/news/uk-politics-50838994|archive-date=31 January 2020|url-status=live}}</ref> L'ampio consenso tra gli economisti è che la Brexit probabilmente danneggerà l'economia del Regno Unito e ridurrà il suo reddito pro capite reale a lungo termine e che il referendum stesso abbia danneggiato l'economia.{{#tag:ref|See:<ref name="NYT Feel Good">{{cite news|url=https://www.nytimes.com/2016/05/22/business/international/brexit-referendum-eu-economy.html|title='Brexit,' a Feel-Good Vote That Could Sink Britain's Economy|last=Goodman|first=Peter S.|date=20 May 2016|work=The New York Times|access-date=28 November 2017|issn=0362-4331|quote=finding economists who say they believe that a Brexit will spur the British economy is like looking for a doctor who thinks forswearing vegetables is the key to a long life|archive-url=https://web.archive.org/web/20171201044816/https://www.nytimes.com/2016/05/22/business/international/brexit-referendum-eu-economy.html|archive-date=1 December 2017|url-status=live}}</ref><ref name=":3" /><ref name="auto8">{{cite web|url=http://voxeu.org/content/brexit-beckons-thinking-ahead-leading-economists|title=Brexit Beckons: Thinking ahead by leading economists|last=Baldwin|first=Richard|date=31 July 2016|website=VoxEU.org|access-date=22 November 2017|quote=On 23 June 2016, 52% of British voters decided that being the first country ever to leave the EU was a price worth paying for 'taking back control', despite advice from economists clearly showing that Brexit would make the UK 'permanently poorer' (HM Treasury 2016). The extent of agreement among economists on the costs of Brexit was extraordinary: forecast after forecast supported similar conclusions (which have so far proved accurate in the aftermath of the Brexit vote).|archive-url=https://web.archive.org/web/20171125093912/http://voxeu.org/content/brexit-beckons-thinking-ahead-leading-economists|archive-date=25 November 2017|url-status=live}}</ref><ref name=":6">{{cite web|url=http://www.igmchicago.org/surveys/brexit-ii|title=Brexit survey|publisher=[[Initiative on Global Markets]], University of Chicago|access-date=1 November 2017|archive-url=https://web.archive.org/web/20171017213942/http://www.igmchicago.org/surveys/brexit-ii|archive-date=17 October 2017|url-status=live}}</ref><ref name=":7">{{cite web|url=http://www.igmchicago.org/surveys/brexit-2|title=Brexit survey II|publisher=[[Initiative on Global Markets]], University of Chicago|access-date=1 November 2017|archive-url=https://web.archive.org/web/20190304001918/http://www.igmchicago.org/surveys/brexit-2|archive-date=4 March 2019|url-status=live}}</ref><ref name=":8">{{Cite news|url=https://www.theguardian.com/politics/2016/may/28/economists-reject-brexit-boost-cameron|title=Economists overwhelmingly reject Brexit in boost for Cameron|last=Sodha|first=Sonia|date=28 May 2016|work=The Observer|access-date=1 November 2017|last2=Helm|first2=Toby|issn=0029-7712|last3=Inman|first3=Phillip|archive-url=https://web.archive.org/web/20171107112444/https://www.theguardian.com/politics/2016/may/28/economists-reject-brexit-boost-cameron|archive-date=7 November 2017|url-status=live}}</ref><ref name="auto9">{{cite web|url=https://www.ft.com/content/c2b0359e-d0dc-11e6-b06b-680c49b4b4c0|title=Most economists still pessimistic about effects of Brexit|website=[[Financial Times]]|access-date=22 November 2017|archive-url=https://web.archive.org/web/20190722161150/https://www.ft.com/content/c2b0359e-d0dc-11e6-b06b-680c49b4b4c0|archive-date=22 July 2019|url-status=live}}</ref><ref name=":10">{{cite web|url=https://www.ft.com/content/dc62922a-204b-11e7-a454-ab04428977f9|title=Brexit will damage UK standards of living, say economists|website=[[Financial Times]]|access-date=22 November 2017|quote=Unlike the short-term effects of Brexit, which have been better than most had predicted, most economists say the ultimate impact of leaving the EU still appears likely to be more negative than positive. But the one thing almost all agree upon is that no one will know how big the effects are for some time.|archive-url=https://web.archive.org/web/20190722161152/https://www.ft.com/content/dc62922a-204b-11e7-a454-ab04428977f9|archive-date=22 July 2019|url-status=live}}</ref><ref name="auto10">{{cite news|url=https://theconversation.com/why-is-the-academic-consensus-on-the-cost-of-brexit-being-ignored-59540|title=Why is the academic consensus on the cost of Brexit being ignored?|last=Wren-Lewis|first=Simon|work=The Conversation|access-date=22 November 2017|language=en|archive-url=https://web.archive.org/web/20171201040705/https://theconversation.com/why-is-the-academic-consensus-on-the-cost-of-brexit-being-ignored-59540|archive-date=1 December 2017|url-status=live}}</ref><ref name="auto11">{{cite news|url=https://www.bloomberg.com/news/articles/2017-02-22/brexit-s-fallout-on-u-k-economy-seen-as-chronic-not-crippling|title=Brexit to Hit Jobs, Wealth and Output for Years to Come, Economists Say|date=22 February 2017|publisher=Bloomberg L.P.|access-date=22 November 2017|quote="The U.K. economy may be paying for Brexit for a long time to come{{nbsp}}... It won't mean Armageddon, but the broad consensus among economists—whose predictions about the initial fallout were largely too pessimistic—is for a prolonged effect that will ultimately diminish output, jobs and wealth to some degree."|archive-url=https://web.archive.org/web/20190722162650/https://www.bloomberg.com/news/articles/2017-02-22/brexit-s-fallout-on-u-k-economy-seen-as-chronic-not-crippling|archive-date=22 July 2019|url-status=live}}</ref><ref name=":12mitchell">{{cite journal|last=Johnson|first=Paul|last2=Mitchell|first2=Ian|date=1 March 2017|title=The Brexit vote, economics, and economic policy|journal=Oxford Review of Economic Policy|volume=33|issue=suppl_1|pages=S12–S21|doi=10.1093/oxrep/grx017|issn=0266-903X}}</ref><ref name="auto12">{{cite news|url=https://www.economist.com/news/britain/21727078-patrick-minford-thinks-gdp-could-increase-68-most-economists-say-brexit-will-hurt|title=Most economists say Brexit will hurt the economy—but one disagrees|work=The Economist|access-date=22 November 2017|language=en|archive-url=https://web.archive.org/web/20171030213649/https://www.economist.com/news/britain/21727078-patrick-minford-thinks-gdp-could-increase-68-most-economists-say-brexit-will-hurt|archive-date=30 October 2017|url-status=live}}</ref><ref name="auto13">{{cite news|url=https://www.independent.co.uk/news/business/analysis-and-features/uk-economic-forecast-brexit-reason-economy-living-standards-wage-loss-households-city-a8072436.html|title=This is the real reason the UK's economic forecasts look so bad|date=23 November 2017|work=The Independent|access-date=28 November 2017|quote=One thing economists do generally agree on is that leaving the European Union and putting new trade barriers between Britain and our largest and closest trading partners is extremely unlikely to boost UK productivity growth—and is far more likely to slow it|archive-url=https://web.archive.org/web/20190722161839/https://www.independent.co.uk/news/business/analysis-and-features/uk-economic-forecast-brexit-reason-economy-living-standards-wage-loss-households-city-a8072436.html|archive-date=22 July 2019|url-status=live}}</ref>|group=lower-alpha}} È probabile che la Brexit riduca l'immigrazione dai paesi dello [[Spazio economico europeo]] (SEE) nel Regno Unito e rappresenta una sfida per l'istruzione superiore, la ricerca accademica e la sicurezza del Regno Unito. A seguito della Brexit, il diritto dell'UE e la Corte di giustizia dell'UE non hanno più la supremazia sulle leggi del Regno Unito o della sua Corte suprema, se non in misura temporanea. La legge dell'Unione europea (di recesso) del 2018 mantiene il diritto dell'UE pertinente come legge nazionale, che il Regno Unito potrebbe quindi modificare o abrogare.
