Maybe never. The oft reported net revenue stream of £11.2bn was in itself a bit of a red herring as that figure was only true for 2013 and almost true for 2018. This ONS article shows the variations since 2010:
https://www.ons.gov.uk/economy/gove...les/theukcontributiontotheeubudget/2017-10-31
Of course then there is the benefit in out trade with the EU, - always a difficult thing to extract a net figure for because it isn't just payments made and payments received. There is also the (presumed) benefit (positive or negative) of the goods and services that the trading brings. We will know just how much we have been benefitted from that when new trading agreements are in place. Depending on how many more or less jobs there are will to a large extent determine whether there is any
real gain or loss in 'taking back control'. I can imagine that might be something that regular leave contributors to this forum might decline to comment on.