Determine Effective Tax Rate

In British Columbia we've been working with a 12% HST (Harmonized Sales Tax) for the past 1.5 years. Effective April 1, 2013, we'll be going back to a system with a separate 7% Provincial Sales Tax (PST) and our national 5% Goods and Services Tax (GST) instead. In our case, we wanted to look at sales that will not be PST taxable under the new tax structure, meaning that the effective tax on these sales will drop from 12% to 5%.

So assuming that we have the following tables in an Excel worksheet and the name of the tax table is tblTaxRates, it's really easy to get the effective tax rate for any date: