It sounds like the tax office system is treating you as a single income couple.
However, based on the low income of your wife, it is more beneficial to retain the home carer's credit of €900 for 2010 than apply for the increased SRCOP, since the increase in the SRCOP of €1600 would only save tax of 21%x€1600 = €336 (as opposed to €900 for the credit).
Under the rules, it is possible for the home carer to have an income of up to €5080 (2010 rate) and retain the full home-carer's credit. The credit is reduced by half of the excess over €5080 (again, 2010 rules- I don't know what change if any occurred in the last budget), so it 'breaks-even' at an annual income of €6880.
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