I read recently that a PCI DSS official recommended a “risk-based approach” to PCI that allows for partial compliance by meeting the compliance obligations in stages. Is there such a thing, and is it a practical way to achieve PCI compliance?

The short answer to your question is no. There is no way to achieve PCI DSS compliance other than to achieve 100% compliance with the portions of the standard that are relevant to your organization. When it comes to PCI DSS compliance, there are no “shades of gray.” You are either compliant or noncompliant.

My guess is the PCI DSS official you read about was referring to the Prioritized Approach to PCI DSS Compliance. This guide is meant to provide organizations with a risk-based approach to becoming compliant by having them address the most important items first, thereby reducing the likelihood of a breach. This approach has six milestones:

1. Remove sensitive authentication data and limit data retention.
2. Protect the perimeter, internal and wireless networks.
3. Secure payment card applications.
4. Monitor and control access to your systems.
5. Protect stored cardholder data.
6. Finalize remaining compliance efforts, and ensure all controls are in place.

The “catch” is milestone six, which basically says, “Do everything else you need to do to become compliant.” To be clear, while this approach allows you to meet specific requirements in stages, it does not mean you are compliant during the process. Your organization is subject to fines and other noncompliance sanctions until you are fully compliant. The PCI DSS Prioritized Approach document sums this up well with a disclaimer reading, in part, “To achieve PCI DSS compliance, an organization must meet all PCI DSS requirements, regardless of the order in which they are satisfied or whether the organization seeking compliance follows the PCI DSS Prioritized Approach.”