Intergovernmental fiscal transfer (IFT) is one of the several sources of funds of sub-national governments. There are two general types of IFT — conditional and unconditional. In many developing economies including the Philippines, the usual existing IFT is a form of unconditional fiscal transfer called revenue shares. In the Philippines, this revenue-sharing scheme is called the internal revenue allotment (IRA). Empirical literature says that unconditional IFTs are the type of fiscal transfers with the least effect on local government spending. The literature posits that the reason for this is that local governments use these transfers to substitute for own-sourced revenues such as local taxes. This explanation was formalized through a framework presented in this paper. Using panel data from Philippine provinces for the years 2001 to 2015, this paper attempted to determine the effect of revenue shares, in the form of IRA, on local government expenditures. Using different econometric methodologies, this paper arrived at several conclusions. First, IRA has a strong positive effect on total local government spending with a marginal effect slightly greater than one — much higher than what comparable studies found using data from other countries. Secondly, the effect of IRA on local government expenditures is even stronger for provinces with relatively greater ability to generate its own funds. Next, IRA and other externally sourced revenues have much stronger marginal effects on local government spending than do own-sourced revenues. Finally, IRA has widely varying effects on different components of local government expenditures.