quite so
Indeed; I completely agree. Primarily heard in UK. A: "This is yet another empty promise from the Tories." B: "Quite so. Next they'll be telling us we won't have to pay taxes anymore!"
quite ˈso
(British English, formal) used to agree with somebody or to show that you understand them: ‘It’s a very interesting book.’ ‘Quite so. That’s why I wanted you to read it.’