The claim that total disposable income equals total national expenditure is a foundational macroeconomic identity (such as GDP measured via the expenditure approach versus the income approach) and represents common economic knowledge that requires no external citation.
The claim states a basic national income accounting identity where total income equals total expenditure (or output). Because this is a definitional identity within macroeconomic theory and basic economics textbooks, it falls under the COMMON_KNOWLEDGE category according to the instructions, and none of the retrieved specialized papers directly test or refute this foundational accounting definition.