在项目开发过程中，软件需求变更（RC）的存在是开发人员提供软件合同设计的关键挑战。因为在存在RC的情况下，对合同要约的决定将影响开发商所花费的项目价格。软件公司的经理必须决定在软件开发中向客户提供哪些合同设计。从一个来自软件外包行业的例子中抽象出来，我们展示了三种设计的软件合同设计，这些设计结合了固定价格和时间与材料政策。具体来说，一家软件公司提供固定价格，但拒绝对RC的修改（合同N），提供固定价格并同意RC并收取额外费用（合同W），或者最初提供固定价格，然后收取额外费用基于响应RC的时间和材料（合同P）。
我们在两个周期的游戏中研究了三个合同设计的战略选择。我们对垄断和双头垄断模型进行了全面分析；我们使用垄断模型作为基础模型来构建双头垄断模型。同时，在双头垄断模型中，我们捕获了两个开发人员之间的九种组合方案。我们以价格为决策变量，描述了在何种竞争条件下合同可以成为开发商最佳决策的条件。此外，在存在RC的情况下，我们提供了有关合同策略和开发人员绩效的管理洞察力。我们的发现表明，由于附加的RC，第二期的水平是否会根据合同设计和组合方案而影响价格和利润。

The presence of software requirement changes (RC) during project development is a critical challenge for the developer to offer software contract designs. Because under the presence of RC, the decisions toward the contract offer will impact to project’s price spent by the developers. Managers of software companies must decide what contract designs to offer to clients in the development of software. Abstracting from an example drawn from the software outsourcing industry, we exhibit three designs of software contracts incorporating fixed price and time-and-materials policies. Specifically, a software company offers a fixed-price but declines the modification for RC (Contract N), offers a fixed-price and agree to RC with additional charge (Contract W), or initially provides a fixed price and then charges an additional fee based on the time-and-material in response to RC (Contract P).
We examine the strategic choices of three contract designs in a two-period game. We carry out a full analysis of monopoly and duopoly models; we use the monopoly model as the base model to construct the duopoly model. Meanwhile, in the duopoly model, we capture nine combination scenarios between two developers. We characterize the conditions under which the contracts can be the best decision for developers in different competitive models with price as our decision variable. Furthermore, we provide managerial insights into contract strategies and developers’ performance under the presence of RC. Our finding states if the level of the second period valuation due to additional RC will influence the price and profit depending on the contract designs and combination scenarios.

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