Services PCI DSS Scoping & Segmentation
+44 20 3996 1505

PCI DSS Scoping & Segmentation Assessment

Scope determines everything in PCI DSS: cost, effort, risk and audit outcome. Every system that stores, processes or transmits cardholder data is in scope, and so is everything connected to it or able to affect its security. Getting that boundary wrong makes compliance either invalid or needlessly expensive.

RedSecLabs combines QSA-grade scoping analysis with CREST-accredited technical testing: we map cardholder dataflows, classify connected-to and security-impacting systems, validate segmentation with real penetration testing, and design the scope-reduction moves, segmentation, tokenisation, third-party offloading, that shrink your assessed environment permanently.

The result is a defensible scope document your assessor accepts and an environment that costs less to secure and validate every year after.

CREST Member Company CREST Penetration Testing Provider PCI SSC Qualified Security Assessor (QSA) Company ISO 27001 Certified UKAS Accredited Certification AICPA SOC 2

Get Your Fixed-Fee Quote

Tell us what needs testing. You’ll get a scoped, fixed-fee quote back the same business day, from a senior assessor, not a sales rep. No obligation, no spam.

✓ Same-day response✓ Fixed-fee, no surprises✓ Senior testers only✓ Retest included

We reply within one business day with next steps. Your details are used only to scope your enquiry, never shared or sold.

✓ PCI SSC QSA Company · ✓ CREST accredited · ✓ UKAS-certified ISO 27001 & 9001 · ✓ IASME Certification Body · ✓ Same-day scoping response
Who this is for

This service is a fit if you’re..

1
Estates with sprawling scope
Flat networks and shared services dragging systems into the CDE that never needed to be there.
2
Cloud & hybrid environments
Confirming segmentation and connected-to scope across VPCs, containers and on-prem under v4.0.1.
3
Cost-reduction programmes
Cutting assessment scope, and annual spend, before the next ROC or SAQ cycle starts.

PCI DSS Scoping & Segmentation, Quick Facts

Last reviewed: 2026-05-21
Covers
CDE definition, dataflow mapping, connected-to and security-impacting classification, segmentation design and validation
Testing
Segmentation penetration testing, annually for merchants, six-monthly for service providers, by CREST testers
Outputs
Scope statement and diagrams your QSA accepts, segmentation test report, scope-reduction roadmap
Reduction levers
Network segmentation, tokenisation, P2PE, iframe/redirect payments, validated third-party offloading
Best timed
Before first validation, before re-architecture, or whenever assessment cost feels disproportionate
Delivered by
RedSecLabs, PCI SSC QSA Company with in-house CREST offensive-security team
CDE
Boundary defined and evidenced
Seg-test
Penetration-tested isolation
Scope
Reduction engineered in
Dataflow
Every PAN path mapped

What is PCI DSS scoping?

PCI DSS scope covers the cardholder data environment (CDE), the systems that store, process or transmit cardholder data, plus connected-to systems and any system that can impact CDE security: authentication servers, monitoring platforms, jump hosts, orchestration tooling. The PCI SSC's scoping guidance makes the entity responsible for proving its scope is accurate every year; assessors then confirm it. Undiscovered PAN flows and misclassified support systems are the most common findings in first-time assessments.

Segmentation is the primary scope-control tool: properly isolated networks remove out-of-scope systems from assessment. But segmentation only counts if it is verified, PCI DSS requires penetration testing of segmentation controls at least annually (every six months for service providers). We run those tests with the same offensive-security team that delivers our PCI DSS penetration testing engagements.

Scope reduction is where the investment pays back: tokenisation, P2PE, iframe/redirect payment architectures and outsourcing to validated providers can move an organisation from a sprawling SAQ D to a compact assessment. Scoping work feeds directly into readiness and the eventual ROC or SAQ.

What PCI DSS compliance delivers:

Eligibility to accept card payments under acquiring bank agreements

Reduced exposure to fines following any card data breach

Lower transaction fees with major card schemes

Cyber insurance coverage eligibility

Customer and partner trust around payment data handling

Evidence reusable for SOC 2, ISO 27001, and broader compliance programmes

Compliance is annual, and the bar continues to rise. v4.0.1 makes scoping accuracy and continuous control operation far more material than under previous versions.

Why PCI DSS matters

Card data breaches remain among the most damaging and costly cyber incidents an organisation can experience. Beyond direct fraud costs, breached merchants face card scheme fines, mandatory forensic investigation by PFI-approved investigators, increased transaction processing fees, and lasting customer trust damage.

PCI DSS is not optional, it is a contractual requirement under every major acquiring bank agreement. Non-compliance can result in fines starting from £5,000 per month, escalating significantly after a breach, and ultimately to suspension of card-acceptance privileges.

Common consequences of weak PCI DSS programmes:

Card scheme fines from £5,000 to £100,000+ per month

Mandatory PFI investigation after any suspected breach

Increased transaction processing fees

Acquiring bank termination of merchant agreements

Direct breach costs averaging £3.4M in the UK in 2025

Brand and customer trust damage following public incidents

Strong PCI DSS programmes reduce breach probability, limit financial exposure when incidents occur, and become a strategic asset rather than an annual overhead.

Who needs PCI DSS compliance?

PCI DSS applies to every organisation that interacts with cardholder data. RedSecLabs delivers across all merchant and service provider tiers:

E-commerce merchants (all levels)

Retail and in-person POS merchants

Payment service providers and gateways

Card processors and acquirers

Cloud hosting providers handling cardholder data

Contact centres processing phone payments

Software providers in PCI scope (payment apps)

Logistics and fulfilment where card data flows

If your organisation touches cardholder data, even briefly, even via redirect. PCI DSS applies. We scope your assessment level and SAQ type as the first step of every engagement.

Our PCI DSS Methodology

An eight-stage methodology covering the full PCI DSS compliance lifecycle, from initial scoping through annual renewal.

01

Scope Definition

We map cardholder data environments (CDE) and confirm which systems are in scope, in connected scope, or out of scope through network segmentation.

02

Merchant Level Determination

We confirm your merchant or service provider level and identify the correct assessment route. SAQ type or full Report on Compliance (ROC).

03

Gap Analysis

Comprehensive review against all 12 PCI DSS requirements with control-by-control evidence sampling and remediation prioritisation.

04

Remediation Support

Hands-on guidance on common weak areas: network segmentation, encryption key management, authenticated scanning, audit logging, secure development.

05

Quarterly ASV Scanning

External vulnerability scanning by approved scanning vendor (ASV) on a quarterly basis, with remediation support between scans.

06

Annual Penetration Testing

Network and application penetration testing meeting PCI DSS requirements 11.4.1-11.4.5, including segmentation validation.

07

Compliance Validation

QSA-led ROC or SAQ validation depending on your assessment route, producing the documentation acquirers require.

08

Annual Renewal & Continuous Compliance

Year-round programme management to keep controls operational, not just compliant at audit point.

Most clients reach first-time compliance in 3-9 months depending on starting maturity and CDE complexity, with annual renewal cycles thereafter.

What you receive

Every PCI DSS engagement with RedSecLabs includes:

  • Scope analysis and cardholder data environment documentation
  • Merchant level determination and assessment route confirmation
  • Gap analysis report against all 12 PCI DSS v4.0.1 requirements
  • Prioritised remediation roadmap with effort estimates
  • Quarterly ASV scan reports and remediation guidance
  • Annual penetration test report meeting requirements 11.4.1-11.4.5
  • QSA-validated ROC or signed SAQ with attestation of compliance
  • Ongoing compliance management and acquirer reporting support

Industries We Serve

We deliver this service across these industries:

E-commerce
Retail & POS
Payment Providers
Acquirers & Processors
Cloud Hosting
Contact Centres
Travel & Hospitality
Petroleum & Fuel

Why RedSecLabs for PCI DSS

PCI DSS rewards depth, not theatre. Our QSAs and PCI specialists have seen every common scoping mistake, every popular workaround that fails audit, and every remediation pattern that actually works. We deliver assessments that withstand acquirer scrutiny, and a continuous compliance programme that keeps your CDE controls operational year-round.

QSA-led assessments across all merchant levels
Scoping and segmentation expertise (v4.0.1)
ASV-grade quarterly vulnerability scanning
PCI DSS penetration testing to 11.4 standards
Annual renewal and continuous compliance support
Acquirer reporting and dispute support

Discuss Your PCI DSS Scope

Book a free 30-minute scoping call. Merchant level confirmation, SAQ recommendation, and fixed-fee quote within a week.

Book a Scoping Call Contact Us

Where to next

Related services and industry packages worth exploring.

PCI DSS UK

PCI DSS USA

PCI DSS Saudi Arabia

PCI DSS UAE

E-commerce & Retail package
Related reading

From the RedSecLabs research blog

From the blog

PCI DSS SAQ vs ROC: Choosing Your Compliance Path

Self-assessment questionnaire or formal Report on Compliance, which applies to your merchant level.

Read on the RedSecLabs blog
From the blog

PCI DSS 4.0.1: What Every Business Must Do

The 64 new requirements, what changes from 4.0, and the future-dated deadlines.

Read on the RedSecLabs blog
From the blog

PCI DSS Compliance Costs: 2026 Breakdown

What PCI DSS compliance actually costs across merchant level and environment complexity.

Read on the RedSecLabs blog

Frequently Asked Questions

Connected-to systems communicate with the CDE (directly or via controlled paths); security-impacting systems can affect CDE security even without a data path, think identity providers, patch management, monitoring and deployment tooling. Both categories are in scope for applicable requirements, and both are routinely missed.

At least annually for merchants and every six months for service providers, plus after any significant change to segmentation controls. The test must demonstrate that out-of-scope networks genuinely cannot reach the CDE, a proper penetration test, not a port scan.

Usually, and often dramatically. Moving e-commerce to a compliant redirect or iframe architecture, tokenising stored PANs, or isolating the payment estate can cut the assessed system count by an order of magnitude. The reduction repeats every renewal, which is why we treat scoping as an investment, not overhead.

The same principles apply, mapped to cloud constructs: accounts, VPCs, security groups, IAM boundaries and shared-responsibility lines with your provider. Ephemeral infrastructure and CI/CD pipelines that touch the CDE come into scope, and we evidence isolation with cloud-appropriate testing.

A well-evidenced scope package, dataflows, classifications, segmentation test results, is exactly what a QSA needs to confirm scope efficiently. Ours are produced by a QSA Company to the standard we would demand when assessing, which is why they are accepted first pass.

A formal scope statement, network and dataflow diagrams, an in-scope system inventory with classifications, the segmentation penetration test report, and a prioritised scope-reduction roadmap with effort and saving estimates.
What you receive

Every engagement includes

  • ✓ Scoping call. A 30-minute call to define scope, timeline, and authorisation boundaries.
  • ✓ Assessment plan. Written plan covering scope, evidence requirements, and assessment schedule.
  • ✓ Findings report. Control-by-control findings with evidence references and remediation guidance.
  • ✓ Executive summary. Board-ready 1-2 page summary with risk ratings and business impact.
  • ✓ Audit-ready evidence. Findings letter formatted for auditors, customers, and supervisory authorities.
  • ✓ Re-verification letter. Remediated gaps re-verified within an agreed window. Confirmation letter included.
  • ✓ Remediation call. A call with our lead assessor to walk through findings and remediation strategy.
How we deliver

Our process, end to end

  1. 1
    Scoping call & fixed-scope quote
    A 30-minute call. We define scope, targets, timeline. You get a fixed-scope quote within one working day. No surprise invoices.
  2. 2
    Assessment plan & authorisation
    Written assessment plan covering scope, evidence requirements and schedule. Authorisation and NDA in place before any work begins.
  3. 3
    Assessor-led execution
    A senior assessor runs the engagement. Material gaps flagged as they are found, not saved for the report. Daily updates if you want them.
  4. 4
    Technical + executive report
    Detailed technical findings with reproduction steps. Board-ready executive summary. Delivered within agreed working days.
  5. 5
    Remediation call & re-verification
    Walkthrough with our lead assessor. Re-verification of remediated gaps within the agreed window. Confirmation letter for your auditors.
Engagement scope

What shapes the quote

Small scope
Single environment, one framework, limited system count. 5-7 working days.
Medium scope
Multiple systems or sites, several control owners, integrations. 8-12 working days.
Enterprise scope
Complex estate, multiple entities or locations, full audit-grade evidence. 12-25 working days.
Fixed-scope quote within 1 working day
No surprise invoices, no scope-creep. We commit to a number before you commit to us.
Sample report
See exactly what we deliver
Download a redacted RedSecLabs report. Same structure, depth and clarity as the deliverables your team will receive.
Download sample report
Why RedSecLabs

Grounded reasons clients choose us

⚑
UK-based team
Testers based in the UK. Data stays within UK/EU jurisdiction for sensitive engagements.
❄
CREST member company
CREST-accredited methodology. Senior testers hold CREST CRT or CCT certifications.
⚙
Practitioners, not checklists
Assessments run by practitioners who also test systems hands-on, findings reflect how controls actually operate.
✎
Clear executive reporting
Reports your board can read and your developers can act on. No jargon padding.
♚
Compliance-aware delivery
PCI, SOC 2, ISO 27001, DORA, GDPR. We map findings to your compliance framework.
↺
Retest support included
Free retest of remediated findings within agreed window. Confirmation letter for auditors.
Related services

Often paired with this engagement

PCI DSS SAQ Assessment →
QSA-verified SAQ and countersigned AOC.
PCI DSS QSA Hub →
All PCI DSS assessment services.
Readiness & Gap →
Gap register and evidence index pre-assessment.
ROC Assessment →
QSA Report on Compliance, end to end.
PCI DSS QSA (UK) →
Formal QSA assessment in the UK.
PCI DSS QSA (US) →
Formal QSA assessment in the US.
PCI ASV Scanning →
External quarterly scans (via ASV partner).
Network Pentesting →
Required under Requirement 11.
Web App Pentesting →
For payment applications.
📞 Call us Book a call