Hmmm, for a salary in the 30K range, taxes shouldn't be 40-45%. That is for much higher salaries. Speaking for myself, I am earning about 42K and my taxes are about 30%
This is the table for 2005:
If your earnings are over (A), then you have to pay a fixed amount of (X), plus a percentage (B) of the difference of your total earnings minus (A). Your total earnings must be lowered by some legal reductions (2400 euros if you are not self-employed, all the money your payed to the National Social Security, certain amount if you have children or elder parents depending from you, etc.). Additionally, some reductions on the total taxes amount can be done, too (a certain % of the amounts payed for your home's mortgage, a % of the donations to registered foundations or NGOs, etc.)
So, you have to find the number immediately lower to your total, and do the maths with that row:
(A) (X) Diff up to (B)
0.00 0.00 4080.00 15%
4080.00 612.00 9996.00 24%
14076.00 3011.04 12240.00 28%
26316.00 6438.24 19584.00 37%
45900.00 13684.32 whatever 45%
Hope it is more or less clear.