Double taxation quiry

Is social security tax considered income that has already been taxed in the UK? In the Netherlands, you pay payroll tax and social security tax -- rather than NIC. It sounds silly as tax is in the name in the Netherlands, but as we in the UK would call this NIC, I've never really thought of it as a tax per se. As social security tax is higher in the Netherlands than the UK and payroll tax lower for me, I just wanted to check whether both are considered tax from a self assessment standpoint or whether it's only payroll tax?

Hi,

Please note that the NIC, social security tax deducted from employment income does not have to be reported as 'tax deducted' on a Self Assessment tax return. You can see information here:                             

National Insurance: introduction

Thank you.