Within Teamwork Projects you can update your payment details directly through your site if you have a current subscription for example, if your payment card has been replaced or you need to change to a different card.
If you need to change or add a tax number, you can follow this information also.
To the top right of your Teamwork Site select 'settings' and then choose 'Subscription':
Click on the 'Update payment details' button under your subscription plan. You will then have the option to update your details as below, first enter your country and whether you have a VAT number. You can also choose your industry however this is optional:
Choose continue and then enter your card details:
Note: only site administrators in the owner company have access to this area.
For more information see: Upgrading your Teamwork Projects plan