The taxable income is net income, tax base of income tax (IR) income should be 92,90€. However, only CSG is deductible, and only up to 4.2 %. The base of IR is refore 95,80 € (100 - 4,2) so that net sum of social contributions is only 92,90 euro.
As of 1 January 2018, CSG on pensions affected will increase by 1.7 percentage points, increasing social levies on se pensions from 7.1% to 8.8 %. Ads conflicting ensued on impact of this increase on basis of IR. The State has announced that increase of CSG would be fully deductible from base for IR.
In case of impact, deductible CSG password to 5.9 % (4,2 + 1,7). Failing that, it remains at 4.2 %. For 100 euros of taxable income, IR is sitting on 94,10 € (100 € - 5,90) in first case and on 95,80 € in second. Remains to wait for finance bill as reducing plate of IR implies a reduction in its amount, and, in end, additional revenues that were expected.