(1) If the obligor fails to perform, following a dunning letter from the obligee that is made after performance is due, then the obligor will be in default as a result of the dunning letter. Bringing an action for performance and serving an order for payment in summary proceedings for a payment order are equivalent to a dunning letter.
(2) There is no need for a dunning letter if
1. a period of time defined in calendar terms has been specified,
2. performance is to be preceded by an event, and a reasonable time limit for performance has been specified in such a way that it is possible to calculate it in calendar terms from the event onwards,
3. the obligor seriously and definitively refuses performance,
4. having weighed the interests of both parties against each other, the immediate commencement of default is justified for special reasons.
(3) The obligor of a claim for payment will be in default at the latest if they do not perform within 30 days after the due date and receipt of an invoice or equivalent statement of payment; this applies to an obligor who is a consumer only if these consequences specifically have been noted in the invoice or statement of payment. If the time at which the invoice or payment statement is received by the obligor is uncertain, then an obligor who is not a consumer will be in default at the latest 30 days after the due date and receipt of the consideration.
(4) The obligor is not in default for as long as performance is not made as the result of a circumstance for which they are not responsible.
(5) Section 271a (1) to (5) applies accordingly to an agreement made in derogation from subsections (1) to (3) concerning the time at which the obligor begins to be in default.