There are 4 levels of PCI DSS compliance. The levels are based on the number and types of transactions your company processes each year. Level 1 is the highest level and it includes companies that process over 6 million transactions or have had a data breach. Level 2 companies process between 1 million and 6 million transactions each year. Level 3 companies process between 20,000 and 1 million transactions each year. Level 4 is the minimum compliance level and is for companies that process fewer than 20,000 transactions each year.