I now have to pay him and ask for an invoice just to experience this :-)
But it's enough to just "talk" to the "Finanzamt" to already get a baseline €1000 tax-deductible expense, without even needing to show them anything. Which makes me wonder, why not just deduct this from all income taxes, if you're willing to grant it to everyone, without any proof.
Sorry for sounding cynical now, but "dumb" and "busy" people are naturally disadvantaged from this system. That's not exactly... helping anyone. Except those who profit from the motto "A sucker born every minute!". But even they'd have more advantages, if their "suckers" had more cash at their disposal...
For most people, the withhholdings match exactly the actual income tax or the December deductions are automatically adjusted so that they are (Lohnsteuerjahresausgleich) so there is no benefit in filing taxes.
Of course the system could be much better but I don't agree with the assessment that they keep money from the poor either purposefully or by negligence.
Furthermore, I did file my taxes as an employee once, and got some €80 back, so I considered it a waste of time.
My student friends at the time swore that I should do this, because of the 1k€ "Werbungskosten", and they also got about €80 out of it, but they were earning far less, so I don't know how the maths behind that is all supposed to work out.
I'm in an entirely different situation now, I run my own company, but no employees, and have yet to talk to a tax advisor. I'll know more by the end of the year, but trust me that there is some (in my subjective opinion, of course, objective) truth in the sentence, that "rich and poor are segregated by tax systems" and this is no coincidence.
If you have the same income each month (and there haven't been changes in law during the year) each monthly payment covers exactly 1/12 of your income tax. So in that case, the December payment is the same.
Do to different circumstances you might still get small sums back, as you noticed