As if in answer to my macro note-making prayers from today's lecture, here's Prof. Menzie Chinn on the national saving identity for the US.
The National Saving Identity states:
CA ≡ (T-G) + (S-I)
Where CA is the current account, (T-G) is the consolidated government budget balance, and (S-I) is the private sector saving-investment balance.
via Econbrowser: The National Saving Identity: Private Saving, Household Saving, and Rebalancing. Read it all there, folks.