In the Income Approach
Net National Product (NNP) is GNP minus depreciation
Net National Income (NNI) is NNP minus indirect taxes
Personal Income (PI) is NNI minus retained earnings, corporate taxes but it includes transfer payments, and interest on the public debt
Personal Disposable Income (PDI) is PI minus personal taxes.
S = personal savings
C = personal consumption
PDI = personal disposable income
TP = personal taxes paid
TPP = personal transfer payments received via governments
PI = personal income
RE = retained earnings
TC = corporate taxes
TPC = corporate transfer payments from governments
IG = interest on the public debt
NNI = net national income
TIN = indirect taxes
NNP = net national product
D = depreciation