As part of its flow of funds accounts, the Federal Reserve Board produces a measure of personal saving based on the difference between the personal sector’s net acquisitions of assets and its net increase in liabilities. This measure shows the same downward trend in personal saving relative to disposable personal income seen in the NIPA measure. A comparison of these measures is available here: http://www.bea.gov/national/nipaweb/Nipa-Frb.asp.
The NIPAs include some additional measures of saving that are broader than personal saving. “Private saving” includes saving by business in the form of corporate retained earnings along with saving by persons. “Gross saving” (also known as gross national saving) includes saving by all sectors of the domestic economy: persons, business, and government gross of depreciation expenses (also known as “consumption of fixed capital,”). Gross saving has declined in recent years, as shown in NIPA table 5.1.
The difference between gross national saving and gross domestic investment represents the external financing that is obtained by borrowing from the rest of world or by sales of U.S. assets to the rest of the world. This difference has grown rapidly in recent years, as is shown by the line, “Net lending or net borrowing” in NIPA table 5.1.