The common assumption is that the UK’s taxation is the source of revenue that pays for public services, health, welfare benefits, education and defence. It is often assumed, and commonly framed as, taxpayers money. I was having quite a discussion on Twitter about this. I was putting forward the idea that taxation is not a source of income. The following justification comes from Larry Randall Wray and is a view held by heterodox  economists who subscribe to Modern Monetary Theory or Modern Money Theory (MMT) (see Mitchell, 2016; Wray, 2015).
Wray explains the principles in the following video. If you want a brief overview read on.
Imagine year zero for a country’s economy, the notional point at which the economy begins. The first thing that the country has to do is invent a currency. In the UK we have the pound. The government creates a currency with which transactions and trade can take place. The government is the only institution that has the legal power to create that currency. Anyone else who tries to faces criminal prosecution.
At year zero, the UK has to introduce that currency into the economy, it can give it to its citizens and it can pay them to provide the things we need for our society. The government pays people to provide administration, build hospitals, schools, sports facilities and weapons. It can pay people who don’t have a job. It can pay people to be doctors, teachers and it can provide training for those individuals. It can pay for research and development.
It is only after the government has introduced currency into the economy that it can tax people and businesses. This flow of spending followed by taxation continues year-on-year. And in fact most of the time the UK runs at a deficit, there is lag between spending and taxation. Because spending precedes taxation. You can see this in the graph below.
So what is taxation for, if it does not provide government its revenue? Wray and other MMTers argue that it creates a demand for the currency, it makes it flow round the national economy. If we did not have taxes then the currency, the pound for example, would not be in demand in the economy. We need it because we have to pay taxes in that currency. Richard Murphy (2015) considers tax a kind of democratic subscription, it gives citizens a commitment and right to participate in democracy. Taxation is also used to redistribute wealth and to regulate inflation by increasing or reducing demand in the economy.
It is important to recognise that running an economy in deficit does not necessarily increase the national debt, because the national debt is not really a debt in the sense that we understand personal or household debt (Wray, 2015). The national debt are bonds created by the government to drain accumulated reserves in the banks. This represents the accumulation of currency in the private sector and technically speaking it is used to maintain the overnight interest rate. This, I understand is common knowledge for anyone in banking or finance.
So when a government talks about maxing out the government credit card, or leaving a debt for our grandchildren this is highly misleading. A government cannot run out of its currency. Therefore, there is really no excuse for not funding health and education and other public services properly.
Related blog posts:
 Heterdox economics contrasts with orthodox or mainstream classical economics.
 0n 22/2/2017 I noticed that this blog had been replaced with an earlier incomplete draft, I have now restored it
 Thank you to Sandra Crawford who introduced me to this excellent illustration of the ideas in this post.