Any “adult” claim can be asserted by an action, that is, the right of the claimant, for whom the time limit for voluntary performance has already expired, typically a claim from an unpaid invoice that is overdue. However, it must not be an already expired claim.

A claim is the right of one person (the creditor) to demand and effectively obtain a specific performance from the other person (the debtor). However, only an “adult” claim is enforceable, that is, one in which the debtor finds himself in default against the creditor. Therefore, if the debtor of an adult claim voluntarily fails to fulfil his obligation, he has no choice but to bring such a claim in due course before the court (which, in particular, will assess whether the debtor's alleged obligation actually exists).

However, it is not possible to sue for still immature claims, as illustrated by the following example from ordinary life: Mr. Novak borrowed CZK 10,000 from Mr. Svoboda and pledged to return it to him by the end of the year. But after a few days, Mr. Svoboda found out that he needed the money himself, so he turned to Mr. Novak to return his money or sue him. Does he have the right to do so? A lawsuit would not succeed at such a moment. Mr Svoboda does not yet have any claim (the agreed due date has not yet come) and if he actually filed the claim, the court would reject it as premature. Mr Svoboda must therefore wait until the New Year (i.e. when the voluntary deadline for performance has expired) and, if Mr Novak does not return the money himself, send him a pre-trial reminder and only then sue him if necessary.

Just as a claim can be made early, it can also be made late. Claims cannot be successfully enforced forever, but they must be asserted in court during the limitation period, after which the debtor may object to the limitation period and the court will not grant such a claim. The statute of limitations still exists, but only in the form of an “obligation in kind”, which the debtor can fulfill at his discretion (however, it will not be a performance without a legal reason, and therefore the creditor will be able to fulfill it according to his will. The debtor may then continue to perform, but he does so completely voluntarily (and this is not an undue enrichment of the creditor).

As a rule, the claim is made in court, but there are other ways in which the claim can be obtained in a particular case. For some claims, an arbitration clause has been negotiated, the parties may agree on an out-of-court settlement, or they may also conclude a notarial or enforcement agreement with a clause of direct enforceability. The latter option is particularly useful where the debtor does not dispute his debt, but needs to break it down into several installments.