Tax Exempt Checkbox
The Tax Exempt Checkbox is only available to users that have the application right "Can Set Tax Exempt Status On Companies". If you do not have this right, the tax exempt checkbox will be disabled (greyed out). Setting this checkbox makes every project and service ticket created have a zero tax rate by default. The tax exempt status can however be overridden on projects with the appropriate right of "Can Set Tax Exempt Status on Projects".
If you set a company to Tax Exempt and the company has a resale #, you should fill out the Resale # text box on the company.