A verbal agreement is valid: but hard to prove.
A contract for work can be concluded orally or merely by conduct under the general provisions of the Civil Code No. 89/2012 Coll.: you agree over the phone, the contractor starts work, issues an invoice upon completion, and you pay it. Such a relationship is valid. The problem arises only when something goes wrong and it becomes necessary to prove what was actually agreed upon.
Without written documentation, the invoice remains the sole record, and it typically describes only the outcome ("bathroom renovation", "website development"), not the conditions under which it was to be produced.
What happens when there is no written agreement
The most common disputes we encounter on contracts without an agreement revolve around the same issues:
- Scope of work - what was exactly agreed and what constitutes "additional work".
- Price - whether it was a fixed amount or just an initial estimate that increased during the process.
- Date - when the work was due to be completed and what happens in case of delay.
- Defects - who and how to report defects that appear only after handover.
Without a written basis, each of these points is resolved from scratch, usually based on "who remembers what" or what can be retrieved from emails and SMS messages. In practice, this means the dispute lasts longer, both parties hire a lawyer sooner than necessary, and the outcome remains uncertain even for the party that is "right" - because they have no evidence to substantiate it.
A verbal agreement is insufficient for the contractor as well.
A missing contract harms not only the client. Without a written agreement, the contractor also finds it difficult to prove that the client approved the scope of work, the deadline, or the price for additional work. Resolutions where the work "does not meet the client's expectations" often end up equally uncertain for both parties, precisely because neither side recorded in advance what they had actually agreed upon.
What a written contract for work covers additionally
A written contract for work typically contains a precise description of the work and its scope, the agreed price and payment method, the completion deadline, conditions for the client's cooperation, the procedure for handing over the work and rectifying defects, and any potential penalties for delays. This is not just an additional formality; it ensures both parties share the same understanding of the job before starting.
For more details on how to specify price, deadlines and deposits in the contract, see our article. Price, deadlines and deposits in the works contract, and how to properly accept an order, in the article Handover of the work and rectification of defects.
When invoicing without a contract usually succeeds
For small, one-off jobs of low value or with a long-standing trusted supplier, many people skip a written contract and in practice this causes no issues. However, the larger, longer or more expensive the job, refurbishment, construction work, software development, long-term cooperation: the more worthwhile it is to have at least a basic written agreement. It does not need to be a complex legal document; often an email summarising the scope, price and deadline, confirmed by both parties, is sufficient.
Beware of long-term cooperation "on invoice".
A special case arises when invoicing effectively replaces long-term, factually dependent work, fixed working hours, a single main client, and subordination to instructions as an employee would be. Such an arrangement may be deemed circumvention of employment law. If you are considering such an arrangement, consult an expert beforehand so you know exactly where you stand.
Summary
An invoice on its own proves that payment for the work has been made, but it does not prove what was agreed, at what price and by what deadline. For larger jobs, it is therefore worth having a contract, at least in basic written form. A ready-made template of a works contract can be found at smlouva-o-dilo-vzor.cz download free here.