Tax issue - posting with input and output tax in same posting

Hi,

we would need to realise a tax key as follows:

Invoice amount 220 $ equals 110%

Tax amount (to pay to tax auth.) 20 $ 10%

Tax base amount 200 $ 100%

input tax: 20 $ equals 10 %

input tax base 200 $ 100 %

input tax: 20 $ equals 10 %

input tax base 200 $ 100 %

The posting would look like this:

Cr vendor 220

Dr expense ac 220

Dr input tax ac 20

Cr output tax ac 20

Has someone done something like this? I am stuck with the settings in tax keys and do not get there.

What I achieved was to have a posting with 2 tax lines were invoice amount equals 100% (but not 110%).

Thanks!

Heinrich