Catalan architect Enric Miralles is to meet an all-party body on Wednesday to discuss whether to accept a building in line with his design or a radically scaled-back version.
The Miralles version, designed to RIBA Stage D, includes about 20 options that will improve the life-cycle cost of the building and keep faith with its green credentials, but at an increased initial cost.
Another version keeps to the planned 拢50m construction budget but at the expense of key aspects of the design and a commitment to use Scottish materials.
The project team, including Bovis, QS Davis Langdon & Everest and Miralles' UK partner RMJM, has been working hard to keep the costs to 拢50m, but will now ask MSPs to make tough choices themselves.
A source at the Scottish Office, which has been acting as client for the project, said the cost-cutting options, which would save 拢5m-10m and keep the project within the 拢50m budget, included:
Inflation, expected to continue at 3% until 2001, is already expected to push the cost of the building up, but the project is now turning into a test case for life-cycle costing.
The project team was unavailable for comment, but industry sources said it had followed Treasury guidance in proving that a higher initial cost could lead to long-term savings. It has also followed the Scottish Office's brief to the letter.
The decisions on the building's future will be made by a body chaired by Liberal Democrat Sir David Steel.
Sir David is acting after MSPs Donald Gorrie and Margo McDonald tabled a motion calling for a review of the project and alleging that its overall cost had risen to more than 拢110m. This includes the 拢27.6m cost of renovating temporary buildings for the parliament, 拢10.5m for fees, 拢10.6m for VAT, 拢4m for the purchase of its site, 拢3.5m for furnishings and 拢4m for IT. A Scottish Office spokesman said reports that the project cost had doubled were "mischief-making".
He said the project team was still working to a budget of 拢50m, exclusive of VAT and fees.
Industry sources said this budget was likely to provide a "perfectly acceptable base-build option, but not a building with the lowest long-term cost".