As our Canadian customers will be aware, there are many variables regarding tax rates on invoices from Canadian suppliers dependant on both the region of the supplier and recipient. This is usually displayed on bills with multiple tax amounts. In order for us to present you with the correct tax on the document, it may require you to change some supplier settings to account for this, so don't be alarmed if a map request is actioned and lands in your Processing tab with an incorrect tax amount. When creating a map for a supplier, we want this map to be available for other Lightyear users. In order for this to be possible, the tax amount is calculated using your company or supplier settings.

When you receive a mapped invoice with an incorrect tax rate, this just means that the tax rate on the bill differs from the default tax rate that is set for your company. Once you have applied the map and sent it to your Approvals tab, the tax should be correct as long as the supplier has the correct tax rate set. You can set this when creating your supplier for the first time 

Or if you haven't done this, you can go to the Suppliers section of your Lightyear account and edit it from there. Please see this article on setting supplier tax rates for more information on how to do this.