Key legal question
Whether the taxpayer could still demand payment of the 1998 tax credit instead of set-off against later taxes.
Extracted holding
The credit had already been validly extinguished by set-off against due later cantonal and communal taxes, so no payment claim remained.
Extracted reasoning
Set-off of matching, due monetary claims is a general principle of public law and also applies in tax law unless excluded. Here, at each transfer point, due tax claims existed, and the taxpayer failed to challenge the non-payment and transfer decisions in time.