Tax Calculation Issue with Magento 1.9.3.8

[jhuebel]

I'm experiencing a weird issue with tax calculations with Magento 1.9.3.8. I'm also using TaxJar to provide tax rule updates. Here's my issue:

We have a tax nexus in the state of Texas. So, when a Texas customer purchases products, they should be charged an 8.25% tax rate. And according to the tax rules currently setup in Magento, any Texas-based customer should been charged 8.25%. However, Texas customers are being charged 8%. I have no idea where Magento is getting this 8% rate.

Here's the Texas tax rule:

Since we also have a nexus in Louisiana, there are a number of tax rules for that state (by ZIP code, since it's destination-based). We also have a tax exempt (0%) rule for Wholesale customers.

There are a few ZIP codes in Louisiana that have an 8% rate, but I don't see how Magento could be grabbing those unless there's a serious bug in tax calculation.

Does anyone have any suggestions on how to troubleshoot this problem? How do I determine how Magento chose the tax rate it used? 

[peteschwager]

Did you ever figure this out?

I think it might be something to do with the way the taxjar module works. I believe it grabs the tax percentage from their system when you have their module enabled for checkout, which could be different than the "backup" rate that is stored in the magento tax rules when their module is not being used for checkout

[jhuebel]

I hired a Magento developer to take a look. It turns out that TaxJar's
SmartCalcs feature was the culprit. It was bypassing the tax tables and the
value it was receiving from TaxJar was incorrect (possibly a problem with
how the value was stored). We simply disabled SmartCalcs and now rely on
the downloaded/synced "backup" tax tables from TaxJar. That seems to be
working well.