Conversion- how to import open invoices with tax lines, I don't want system to calculate tax for con

Hello Everyone,

I want to convert AR open invoices with tax lines-  any inputs...what all tax information I need to populate? and what setups are required?

There is an option at transaction type called 'Default Tax Classification', even when I disable that check-box at transaction type, still system defaulting the tax code and calculating tax at invoice.