Since the Accession of His Majesty King George III in 1760, each Monarch has signed over the income from the Crown Estates to the Government, saving the Duchy of Lancaster for the Monarch and the Duchy of Cornwall for the heir-male of the King or Queen.
In other words, the Monarch turns over the revenues from the vast majority of Crown Lands, which by right belong to the Crown, in exchange for what until 2012 was called the 'Civil List', and is now entitle the 'Sovereign Grant'.
So how much money does the 'taxpayer' make off of Her Majesty? Well here are the figures from the most recent reports:
The Crown Estate, has today (25 June 2019) announced another year of strong financial performance, with £343.5m of income returned to the Treasury for the benefit of public finances, up 4.3% from £329.4m in 2017/18. (Source, the Crown Estate)I'm no mathematician, but my trusty on-screen calculator tells me, that far from the Sussexes or anyone else in the Royal Family receiving 'taxpayer money', in this last reporting period, the taxpayer received £261,300,000 from the Queen!
Sovereign Grant 2018-19 £82.2m (Source, The Sovereign Grant and Sovereign Grant Reserve: Annual Report and Accounts 2017-18 (PDF) (Report). Her Majesty’s Stationery Office. 27 June 2018. p. 2.)
So, whenever you hear some republican nitwit spouting about 'how much the monarchy costs', point out the facts!