Yeah, it doesn't include what comes back to us.
So, let's think about this for a second. Let's give the leave campaign the benefit of the doubt and say that leaving the EU will not have a negative impact on the economy, even in the short term.
We stop paying £350m/week to the EU. Great! But we're no longer getting anything back under the Common Agricultural Policy. Our agricultural economy can't survive without those subsidies. So either we have to maintain the existing levels of support which are currently paid out under the CAP, or we let the farmers go bust. If we let the farmers go bust we will be almost totally reliant on imported food, which isn't great from a food security point of view. So let's say we agree to maintain the existing levels of agricultural subsidies. That money has to come out of the same pot that £350m/week is going into. So we don't have a net gain of £350m/week any more.
OK, what else? How about scientific research? We are currently world leaders at this, but being in the EU is a big part of that. Our top scientists work in collaboration with top scientists from other member states, and get much better results that way. Fine, maybe they will still want to collaborate with us. Why wouldn't they? But we won't get any grant funding from the EU so we'll have to find it ourselves, out of what's left of the £350m/week after we have paid our agricultural subsidies. We could choose not to be involved, but then we will no longer be world leaders in scientific research, and we will experience a brain drain as all our top scientists go to work abroad. Our university science departments will lose their prestige and no longer attract top students from all over the world, many of whom pay high international fees on which our universities depend. So we would probably want to give some extra funding to our universities to make up for it. Or not. We could always just put regular tuition fees up to £20k per year to fill the hole. Except that (1) this will also cause a brain drain as our brightest and best students choose to study abroad instead and (2) even with fees at their current level, most students will never pay off their debts so student finance is already a black hole which will continue to grow.
So there's not much of that £350m/week left now, is there? But at least we can spend it on what we want to spend it on, without being dictated to by the EU, right?
Oh. The leave campaign are promising to spend the whole £350m/week on the NHS. Awkward. Even though others have said the farmers and the scientists won't lose their subsidies and grants.
So even in a best case scenario, this £350m/week (like Scotland's famous North Sea oil revenue) seems to have already been spent several times over.
And in a worst case scenario, if all the economists and experts are right, and our economy does suffer, and our tax revenues are down, we are not even going to be £350m/week up in the first place. Because it all comes out of the same pot, at the end of the day.