That is true, but Portuguese citizens make a bigger effort to pay those taxes than French, German, Swedish... Tax take as a % of GDP doesn't tell the whole story.

Er...I might be misunderstanding something here - but it literally does?

Something like tax rates statistics wouldn't tell you whether those taxes are actually paid - but tax revenue statistics do exactly this.

I will provide a clarifying example:

Imagine a person in Portugal has a 1000€ salary, and the state takes 40%, the person has 600€ to live.

A person in Germany gains 3000€, the state takes 60%, the person has 1200€, double the Portuguese.

Cost of living in Germany is higher, but not twice that much. And the cost of living already factors in some taxes, such as VAT, so it's not an apples-to-apples comparison.

Ah, now I understand what you meant with "effort", i.e. that the disposable income after taxes normalized for purchasing power would be lower in Portugal than e.g. in Sweden, right?

Hm...that's a good point actually - net PPP-adjusted household displosable income is definitely lower in Portugal: http://www.oecdbetterlifeindex.org/topics/income/