If a an association or any other organisation is not VAT registered mark it as such under Company Settings - Company information. You find the Settings in the right hand menu. See below.
This will save you time by automating the VAT handling.
When the organisation is marked as "Not VAT Registered", all supplier invoices will automatically get a VAT rate of 0% as default value.
If there is a need to pay VAT for a certain supplier you can always change the VAT rate manually in the supplier invoice in question.
Note: The "not VAT registered" setting will override the interpretation of the VAT registered in the invoice made by the AI.
If a company later becomes VAT registered, you can change the settings and save.
Please note that you will need to enter the VAT Number for the company when you want to see and use the VAT report.