A provisional sum is an allowance included in a cost plan or contract sum for work that cannot be priced precisely at the time of contract signature, because the scope is not yet defined. It is a placeholder figure, not a price. JCT recognises two types: defined provisional sums, where the scope is known well enough to produce a programme allowance, and undefined provisional sums, where it is not. The actual cost is established once the work is fully scoped and quoted, and replaces the provisional sum in the final account. Provisional sums appear most often in heritage and renovation projects, where investigations during pre-construction reveal scope that could not be specified beforehand. A cost plan heavy with provisional sums is a signal that the design is not yet developed enough to commit to a fixed price. Myrmex manages provisional sums inside the PCSA process, with the aim of converting as many as possible into fixed-scope items before the main contract is signed.