It may be fair to broadly define middle income to either side of this, say €17,500 - €60,000, however if it was based on amounts of people working it would give a more accurate range for the middle third of the workforce
I think it will give a good reflection of our own personal attitude to money and salary, as although you may consider yourself middle income you may be in the top third of the workforce
In 2004 the numbers you are looking for are (roughly) 0-15,700; 15,700-33,500 and 33,500+.
The bottom third of earners have about 8% of total income and 0.4% of total tax paid; the middle third have 24% of income and 11% of tax and the top third have 68% of income and 89% of tax paid. The 3.42% of earners over 100K pay 35% of total income taxes collected.
Off the original topic I know but there's lots of useful info in these tables - for example, people earning over 100K contribute an average of 53K each in tax - and yet some posters on other threads think that free college fees somehow mean that the 'average' taxpayer (paying an average of €5,145 each in total or €8,010 for those above 17K income) subsidises the children of these taxpayers....