Migrant Tax?

After reading the news today, I was informed that there will be a 'migrant tax' to help the government in getting more than £500 million a year. This is to help public authorities like the NHS to ease their burden.

I think the government is trying its best to 'claim' money from people who comes from outside EU. I mean, the government could not impose tax on those people who are EU citizens due to free movement of persons. What else that they can do then? Well, they can start imposing taxes on those people who are coming from outside the EU.

If I am not mistaken, the largest influx of migrant population comes from Poland and the rest would be from other EU countries. My question would be why the government is targeting certain quarters only? Sometimes I just don't understand the reason behind it. All that I can come out of this is because the government had no choice but they have to do so.

What a shame... £50? Is it going to be a one off payment or per year? How is it being calculated then?