I assume that you have been claiming Single-Parent Social Welfare up to now , and this means you have likely pay of around € 9,000 for 2010 so far .
When you apply for a tax credit certificate , it is possible that this amount may be deducted from your allowances .
If so , your tax cert would look like this :
Personal Tax Credit€1,830
One Parent Family Tax Credit€1,830
PAYE/Employee Tax Credit€1,830
Total Tax Credit€5,490
Less SW € 1,800
Total TAx credit = € 3,690
This would take your tax-free allowance down to € 354.00 weekly - and therefore you would have some taxable income .
Your Standard-Rate Cut-off point would also be reduced accordingly .
This is my opinion , and open to correction from the guys above , and is based solely on the assumption that you have other earnings for 2010 .