First you have to be subscribed to TACT Online (submit your order via https://tact.iata.org/OrderForm) before you receive a confirmation email with your login credentials.
If you have already subscribed to TACT Online, received and paid your invoice, but did not receive a confirmation email with login credentials (also check your junk/spam mail folders), please contact our Customer Service via the Reach Us option (https://portal.iata.org/s/support-reach-us ). Remember to always include your subscription number when you contact us.
