(b) the amount of consideration to

(b) the amount of consideration to be paid in one contract depends on the
price or performance of the other contract; or
(c) the goods or services promised in the contracts (or some goods or services
promised in each of the contracts) are a single performance obligation in
accordance with paragraphs 22–30.
Contract modifications
18 A contract modification is a change in the scope or price (or both) of a contract
that is approved by the parties to the contract. In some industries and
jurisdictions, a contract modification may be described as a change order, a
variation or an amendment. A contract modification exists when the parties to
a contract approve a modification that either creates new or changes existing
enforceable rights and obligations of the parties to the contract. A contract
modification could be approved in writing, by oral agreement or implied by
customary business practices. If the parties to the contract have not approved a
contract modification, an entity shall continue to apply this Standard to the
existing contract until the contract modification is approved.
19 A contract modification may exist even though the parties to the contract have a
dispute about the scope or price (or both) of the modification or the parties have
approved a change in the scope of the contract but have not yet determined the
corresponding change in price. In determining whether the rights and
obligations that are created or changed by a modification are enforceable, an
entity shall consider all relevant facts and circumstances including the terms of
the contract and other evidence. If the parties to a contract have approved a
change in the scope of the contract but have not yet determined the
corresponding change in price, an entity shall estimate the change to the
transaction price arising from the modification in accordance with paragraphs
50–54 on estimating variable consideration and paragraphs 56–58 on
constraining estimates of variable consideration.