Only if you reserve the right in advance in the agreement and observe the statutory limits. Against consumers, a term allowing the trader to change the contractual terms unilaterally without a ground agreed in the agreement, or to increase the price substantially without the consumer being able to withdraw, is unfair. For open-ended agreements the Act expressly permits a reserved change of terms where the trader gives written notice a reasonable time in advance and the customer may terminate free of charge as of the date the change takes effect. Between businesses the agreement governs; in Czechia the Act itself sets out when a supplier may change its standard terms.
Hosting and development costs are rising and a SaaS provider wants to increase the price of every plan from the start of the new quarter. Its customers, however, hold subscriptions ordered at the original price, and the terms either say nothing about price changes or contain only a general sentence reserving the provider’s right to change the terms at any time. That sentence will not increase the price. What matters is whom you sell the service to and for what term the agreement was concluded.
Consumers: change only on an agreed ground and with a right to leave
A consumer agreement must not contain unfair terms, and such terms are invalid (Section 53(1) and (5) of the Civil Code). The Act treats as unfair in particular provisions allowing the trader to change the contractual terms unilaterally without a ground agreed in the agreement, or entitling it to increase the price without the consumer being able to withdraw where the original price is substantially exceeded (Section 53(4)(i) and (j)). For open-ended subscriptions the Act provides an express exception:
A term under which […] the trader reserves the right to change unilaterally the terms of a consumer agreement concluded for an indefinite period is not unfair under subsection (4)(i) if the trader is required to inform the consumer in writing, a reasonable time in advance, of the change and of the consumer’s right to terminate the agreement, and if the consumer has the right to terminate the agreement free of charge as of the date the change takes effect.
— Section 53(16) of Act No. 40/1964 Coll. (unofficial English translation)
The rule on price increases under point (j) also does not apply to a price-index clause, provided it is not contrary to law and expressly describes the method of price adjustment (Section 53(17)(c)). For a fixed-term subscription, for example an annual one paid in advance, it is safer to apply the new price only from the following period. Where a subscription renews automatically, give the customer enough time to consider the change; a term allowing an unreasonably short period in which to express agreement with renewal is also unfair (Section 53(4)(n)). Which other sentences in consumer terms will not stand is summarised in our answer on invalid clauses in standard terms.
Business customers in Slovakia: the agreement governs
The Commercial Code contains no general rule on unilateral changes to standard terms. Standard terms become part of an agreement by reference, and diverging provisions in the agreement itself prevail over them (Section 273). A price change is a change to the agreement; without a contractual mechanism you need the customer’s consent. Where a written agreement reserves changes to written agreement only, it cannot be changed in any other way (Section 272(2)).
The contractual mechanism must be sufficiently specific: on what grounds and by what key the price changes, for example by reference to the consumer price index, how much notice you will give and in what form, and whether the customer may terminate before the change takes effect. A customer who knew at signing how the price would develop will find it hard to challenge a change that corresponds precisely to that.
Czechia: the Act sets the conditions for change
The Czech Civil Code, in Section 1752, allows the parties to agree that a party which, in ordinary commercial dealings with a larger number of persons, concludes long-term agreements for repeated performance of the same kind under standard terms may change those terms to a reasonable extent, where a reasonable need for a later change already follows from the nature of the obligation at the time the agreement is concluded. The arrangement is valid if it determines in advance how the change will be notified and gives the customer the right to reject the change and terminate the agreement on notice sufficient to obtain another supplier. A provision attaching a special burden on the customer to such termination is disregarded. Where the extent of changes has not been agreed, changes brought about by circumstances the provider must have anticipated when the agreement was concluded, or by a change in its personal or financial circumstances, are also disregarded. As regards price, it is therefore safer to agree a specific adjustment mechanism in the agreement itself than to rely on a general power to change standard terms.
How to proceed
Before increasing a price, check what your terms actually say and separate consumers from business customers. Give notice of the change in writing, with the date on which it takes effect and information on the right to terminate, and for subscriptions paid in advance apply it from the following period. We prepare terms with a price-change mechanism that works in Slovakia and in Czechia under our SaaS agreement and terms service; if you face the same issue with other subscription services, general terms and conditions will help.
This answer provides general information on the law as at 12 September 2026. It does not constitute legal services or replace an assessment of an individual case. The details of your situation may differ. Book a consultation to discuss them.
