The QBO errors that we see related to taxes are usually caused by the Tax Rate in QBO not maching up with what we have in Recurly. What you can do is pull up the erring Invoice and check the way the tax rate is typed out. Then, you would go to your QBO account and add the Tax Rate via Taxes -> Sales Tax -> Setup Sales Tax and then ensure that the tax name is exactly the same as the tax on the Recurly invoice. If anything is off, we will not be able to sync the invoice so make sure you double check this. Once you have this setup, you shouldn't see any issues with syncing invoices with that tax rate.