This study makes two contributions to the literature on portfolio mode
ls and the analysis of state finances. First, the study applies recent
developments in time series analysis-unit root tests for stationarity
-to develop more efficient estimates of tax growth and tax instability
than heretofore. Second, the study extends the conventional tax portf
olio model, which balances the portfolio mix to maximize stability for
selected growth targets, to encompass a third tax policy goal: vertic
al equity. The model is applied to New York State to demonstrate its p
ractical usefulness as a fiscal tool for state policy analysts.