You can choose the Tax as Out of Scope if there is no tax involved and save the transactions in QuickBooks.

I would request you to raise a support ticket in case the issue doesn’t get resolved.

https://contactus.intuit.com/en_IN/contact

We are hoping that you should be able to save the transactions […]

Resolution for 'choose tax issue: 'IN : I am trying to add a bank transaction via banking window. QB is not allowing me to add it and asking me to choose tax for the transaction.' available: Yes.

The choose tax issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the choose tax issue yourself by looking for a resolution described in the article. If it is a complex choose tax issue or you are unable to solve the issue, you may contact us by clicking here or by using other choose tax support options.

For more information about resolving issues related to choose tax in Quickbooks/QBO or to get support for the issue 'IN : I am trying to add a bank transaction via banking window. QB is not allowing me to add it and asking me to choose tax for the transaction.', click the link below: