Amendments to pre-existing contracts are often written in tight templates using precise legal wording that clearly states what aspects of the original contract are being modified and which ones are being upheld. According to Ball State University, contracts can be amended only if all parties consent.
The Nolo Legal Encyclopedia states that amendments to contracts may add to, delete or correct any aspect of a contract. Any amendment must specifically state the paragraph, sentence or even phrase being changed so that there is no confusion between parties. Typically, following the amendment, there is an additional clause that reiterates that parts of the original contract not specifically changed by the amendment remain in effect.
In many ways, an amendment to a contract is like a new contract or a new draft of the original, and so all of the rules for contract writing are upheld for amendments. The U.S. Small Business Association states that in a legally binding contract, the parties involved must each promise something of value to the other, and everyone signing must have the capacity to provide consent to the agreement.
In most cases, all the parties who signed the original contract must also sign the amendment. According to KMStandards, some contract amendments require more than just the parties involved to sign, and some only need one party to sign, as in the case of a one-party amendment.