Here we go, nice interesting article about contributions.
Country would be better off if it was the native British who emigrated...
The Fiscal Impact of Immigration in the UK - Migration Observatory
This one already been disputed.
EU 15 country members more likely to be in UK for salaried jobs and so not claiming benefits etc. Also newer member countries likely to be doing lower paid jobs and get benefits etc. 2 of these countries (Poland and Romania) account for nearly 50% of the total EU people residing in Britain.
Also these figures don't include the outflow of cash (particularly from the 2 countries mentioned) back to their own countries.
Only looks at 2 types of benefit as well and makes no allowance for cost of services.
Snapshot economics that don't show the full picture don't prove much.
Makes no allowance for long-term costs inc. education, health,pensions etc.
Weighed against all this is the fact that these newer member country nationals are filling large areas of lower paid work that employers were struggling to fill adequately from the "domestic" pool of labour. Comparisions with "domestic" equivalents show a higher level of education in that labour pool as well.