I really don't know about Lebanon, but I can assure you that both France and the US (at least) have an incremental tax system. The more you earn, the higher your tax rate.
The system is fairly common.
At the same time, a quick Google search brings some interesting results:
- from this website:
taxrates.cc
1 to 6,000,000 2%
6,000,001 to 15,000,000 4%
15,000,001 to 30,000,000 7%
30,000,001 to 60,000,000 11%
60,000,001 to120,000,000 15%
More than 120,000,001 20%
-
This PDF from the Ministry of Finance website gives the same numbers for income tax.
I'm not sure the numbers are 100% up-to-date though.
Also, the way they are calculated is (usually) not a total percentage. Again, I only know about France, but I wouldn't be surprised it's the same in Lebanon. What I mean is the following:
Suppose you earn 20.000.000 LL, you would pay:
(2% * 6.000.000) + (4% * 9.000.000) + (7% * 5.000.000) = 830.000 LL
Whereas 7% * 20.000.000 = 1.400.000 LL, almost the double.
For what it's worth, I think these values are yearly and not monthly.
Also keep in mind that the income tax is probably not the only thing taken off your salary. There should be other parts taken for social security (ضمان) and/or retirement (تقاعد) and others, ...
There are also, like xterm mentions, parts paid by the company on your behalf, but I don't know if they are included in the above calculation or not.
Again, all I'm saying, except the figures I got from the Lebanese ministry, comes from my understanding of how things work in France, but it's a fairly standard system.