Employer's cost estimate (kosztorys inwestorski)
An employer's cost estimate is the client-side pricing of the planned works, built from the bill of quantities and unit prices. In Polish public procurement it establishes the value of the contract and has to follow the method set out in a ministerial regulation.
For a public contracting authority the document is mandatory: it drives the estimated value of the contract, the procedure used, and whether the bids received fit the amount the authority intends to spend on the works. On a private investment it plays the same role informally, as the benchmark against which contractors' bids are read.
It is calculated from the bill of quantities. Each item takes a unit price from a price database, usually Sekocenbud or Intercenbud, or a price built from KNR norms and the firm's own factor prices (labour rate, material prices, plant) plus overheads. A contractor's bid estimate comes out differently, because the contractor uses its own prices and its own margin.
The most common trap is a stale price database. An estimate based on prices from six months ago drifts away from a market with moving steel and concrete prices, and the tender is annulled because even the cheapest bid exceeds the budget. The second trap sits in the quantities: the unit price can be perfect and the total still wrong, because the quantity came from a superseded drawing revision.
For a general contractor the employer's estimate shows how the client counted the scope, which item is generous, and where there is no item at all for work that will have to be done anyway. That last case comes back later as extra works and a record of necessity.