Multiple tax rates apply to a company. Federal /state statutory tax rates, Effective tax rates, marginal tax rates, etc.
- Federal /State Statutory Tax Rate: Every country and state that a company is domiciled in has a tax rates prescribed by law. In most countries, different tax rates apply based on the level of income or size of the company, type of income, etc.
- Effective Tax Rate: Effective tax rate is the tax expense divided by the pretax income of a specific year. The taxes expense of a company is arrived at according to the statutory tax rates and tax slabs applicable to the company. If the company earns income from multiple countries, multiple statutory tax rates and tax slabs will apply to different portions of income according to local laws and intercountry tax agreements such as double tax avoidance agreements.
- Marginal Tax Rate: The marginal tax rate is the tax rate applicable to the last dollar (marginal income). This marginal tax rate is usually the tax rate applicable to the highest slab that applies to the tax-payer.
This article addresses the question: What are the drawbacks of using marginal tax rates in forecasting cash flows?
The marginal tax rate is usually the tax rate applicable to the highest slab that applies to the taxpayer. Since the tax rates increase as you move up the tax slabs, the marginal rate will be higher than the effective tax rates a company will pay. This difference between the marginal rate and effective tax rate will be large if the company’s income is not much larger than the highest tax slab. The difference between the marginal rate and effective tax rate will become closer to zero as the company’s income gets bigger.
So, in summary, using the marginal tax rate in forecasting cashflows is alright if the company is large. However, if the company’s income is not significantly larger than the highest tax bracket, it may be more appropriate to use the effective tax rate.
Please note that the effective tax rate is also different from the marginal tax rate due to deferred taxes. If a company has a lot of deferred tax assets or liabilities, these must be accounted for in a separate deferred tax schedule in your model.