A prime cost item, usually shortened to PC item or PC allowance, is an amount set aside in a quote for buying a fixture or fitting that has not been selected, or whose price is not yet known, when the quote is accepted. Typical examples are tapware, a vanity, a stove, a toilet suite, door hardware or light fittings. The allowance covers supply only. The labour to install the item is part of your quoted price, because you know what fitting a tap involves even if you do not know which tap. When the customer makes their choice, the price is adjusted by the difference between the allowance and the real cost.
A PC item differs from a provisional sum, which is an allowance for work, not just supply, where the extent is unknown. Some states' home building laws require PC items and provisional sums in domestic building contracts to be reasonable estimates, and say what the contract must state about them. Check with your state's fair trading or building body if you use them on residential building work.
In practice
A bathroom renovator includes "PC allowance, tapware supply, $1,200" in a quote, and states in the note that anything over the allowance is charged at cost plus 10 per cent, and anything under it is credited at cost. The owner chooses a set costing $1,650. The difference is $450, plus $45, so $495 is added through a variation. Had the owner chosen a $980 set, the $220 difference would have come off the final bill.
The trap with PC items is the allowance that is set low to make the quote look cheaper. A customer who discovers that no tapware in the showroom costs $400 feels misled, and in states that require a reasonable estimate, they may have a point. Set allowances from what your customers actually choose, not from the cheapest thing in the catalogue, and tell them which range the figure is based on.
In Quote Desk
Put the allowance on as a typed-in line whose description says it is a PC allowance and what for, so it reads differently from your fixed lines. The note carries the rule for adjusting it, which the customer accepts with the price. The quote builder shows how typed-in lines work.