I am looking to work with a NetSuite developer (hourly contract) with TaxJar experience. Does anyone have experience in this area or have someone they can recommend?

I'm not the guy you are looking for - but I was looking into this for a client and it seemed like they had an integration that was pre-built? Did that not work?

There is a pre-built integration that is very easy to setup. After over a year with taxjar I have personally identified 10-15 use cases where the tax calculation or behavior is incorrect. Sometimes these aren't identified right away and we have ended up with thousands of impacted transactions that need to be updated as well as significant overpayments to the states which they are asking me to pay to file amendments for. I am an Accountant by trade and my skillset at writing scripts that would allow us to mass correct these transactions is very limited. I am hoping to find someone who can help us fix the few thousand transactions impacted by 3 different "groups" of issues other than manually adjusting each record.

The best way to go in my opinion is to create a custom GL plug-in that will consider each use case and will create debits and credits on the transactions accordingly.

It probably depends on what it is doing incorrectly

I'm not a huge fan that GL plugins can't be developed with SuiteScript 2.1 yet, but it's definitely a powerful tool. Many countries can only have taxes properly calculated in NetSuite because of GL plugins. Since TaxJar is a bundle and assuming all the configuration is done correctly, it could be a gap on the app. For sure the best way to go is to have the tax determination app working correctly for all different scenarios, but if there are gaps it could take a long time for TaxJar to fix it. If that's the case, my recommendation would be to have a GL plugin in place supporting any scenario that is not supported by TaxJar yet.