The ICTAD Formula Method was introduced in 1993 to reimburse contractors for price fluctuations in materials, labor, and plant costs during construction projects. There are two formulas - one for contracts exceeding 10 million rupees and one for contracts below that threshold. Both formulas calculate price adjustments based on the valuation of work done, non-adjustable costs, input price indices for materials, labor and plant, and base versus current index values. Input percentages reflect the cost contribution of each material, labor, and plant category.