VAT variable name

could you please help me to add a column for vat on the Sales invoice line.
Anybody let me know the accessing manager built in and custom tax code variable name.

When creating custom themes, you are on your own. This forum is not intended to be for coding support.

But why do you want to add this column? So far as is known, this is not a requirement anywhere in the world. The requirement is to show the tax rate that is being applied, not the tax amount. Tax amount shows in the totals section.