Question juridique clé
Whether moratory interest on late or unpaid tax installments is compatible with the federal law principle on default interest.
Solution extraite
Yes. The installments are legal debts; once unpaid after the payment deadline, the taxpayer is in default and moratory interest may be charged without prior reminder.
Motifs extraits
The obligation to pay installments is a substantive tax-payment duty. Interest on default is a general principle of law also applicable in public law. Because the installments are due and payable before the general tax due date, non-payment after the payment period places the taxpayer in default.