backbone - n. the most important or strongest part of something

refundable tax credit –n. a tax credit that people can claim that is not tied to how much tax they have to pay

consequential –adj. important

check –n. (often) a piece of paper representing a payment from someone to someone that is carried out through a bank

promote –v. to make people aware of something; to make something more popular

provision –n. a condition that is included as part of an agreement or law