New figures have been released showing how much Britain sends the EU every week.
And it's not exactly £350million, despite what Boris Johnson's big red Vote Leave bus said last year.
Britain made a net contribution to Brussels' budget of £156 million a week in 2016/17 - the lowest level for five years.
The total amount for the 12 months to March 2017 was £8.1bn, down from £10.8bn the year before and £9.2bn the year before that.
Labour MP Chuka Umunna, of the pro-Remain Open Britain group, said: "These figures show that you shouldn't believe everything you read on the side of a bus - or that you hear from Boris Johnson's mouth.
"Brexit will mean less, not more, money for our public services."
So what's going on here?
Boris Johnson thinks we send £350m a week to the EU. Is that true? No, it isn't
So why is there such a huge gap between what the Brexiteers said and the truth?
It's because last year, Vote Leave used the gross figure of how much Britain owes to the EU, without counting anything we get back.
In 2016/17 it was technically £16.9bn, or £325million a week - close to what appeared on the big red bus.
But this does not count the UK's automatic, locked-in rebate, which was won by Margaret Thatcher in the 1980s and has existed ever since.
This is important because it's kept by Britain and isn't actually handed over to the EU.
Last year the rebate was £4.8bn. Once it's factored in, this brings weekly contributions down to £234million a week.
But that still isn't the whole picture...
That still doesn't count EU payments to Britain through the public sector - subsidies, for example, or development funds.
The Treasury report says the EU had a £4.1bn benefit to the public sector last year, higher than in any of the last five years except 2014/15.
Once this is factored in, Britain's net contribution was £8.1bn - or, as stated above, £156million a week.
...And that's not the whole picture either
The precise amount of money the UK sends to the EU is difficult to calculate.
EU payments that are made directly to the private sector, such as universities and research organisations, are not included in today's figures.
A briefing paper published last week by the House of Commons Library said that UK organisations receive up to £1.5bn a year.
This includes funding for research and innovation as part of the Horizon 2020 programme, and money for education, training, youth and sport through the Erasmus+ scheme.
This would bring down the £156million-a-week figure still further.
Why is this still important?
David Davis is working very hard over the divorce bill in Brussels
Britain is leaving the EU in March 2019 - but will still have "obligations" after that, Tory ministers have admitted.
The subject of payments is likely to play a crucial role in working out the UK's so-called Brexit "divorce bill".
Downing Street has sought to play down speculation Theresa May would be prepared to pay £36bn in exchange for a deal on trade.
Remainers have reacted exactly as you expect
Britain's contributions to the EU in full
Responding to today's figures, Lib Dem MP Tom Brake said: "Not only have the Brexiteers failed to stump up this extra cash, but it turns out the UK's contribution to the EU was less than half what they claimed.
"This contribution pales in comparison to the economic benefits we get from being part of the single market and customs union.
"The best way to ensure the NHS receives the funding it desperately needs is to prevent an extreme Brexit that would blow a massive hole in the public finances."