An allowance is a provisional amount included for an element that has not yet been fully determined. Its description should explain what the amount covers and how the final selection or execution will be accounted for.
How this term relates to your project
In an extension quote, unselected materials or incompletely defined work may appear as allowances. Look beyond the amount to the scope: does it cover supply, installation, associated junctions or a combination? Two allowances with the same label can represent different packages of work. Ask which assumptions underpin the figure and when the final selection is needed.
Agree who will provide the actual cost information before a decision is made. An allowance does not establish that every possible solution falls within the same total. Compare competing quotations by content first and record the choices still outstanding. Once the selection is made, keep its specification and the corresponding financial agreement together in the project records.