SOC 2 vs ISO 27001: which to do first, and the bundled cost.
They are not interchangeable
SOC 2 is a CPA-issued attestation under AICPA standards. ISO 27001 is a certification issued by an accredited certification body against an ISO standard. The audiences differ: SOC 2 is the dominant signal in US enterprise sales, ISO 27001 is the dominant signal in EU, UK, and international B2B. The procedures differ: SOC 2 has Type 1 and Type 2 with an observation window, ISO 27001 has Stage 1 and Stage 2 with a recurring three-year certification cycle.
The control sets overlap by roughly 80 percent. The SOC 2 Common Criteria map cleanly onto ISO 27001 Annex A. That is why concurrent programmes save substantially on the combined engagement, even though the reports themselves are produced separately.
Cost comparison standalone
| Year | SOC 2 Type 2 | ISO 27001 |
|---|---|---|
| Year 1 all-in | £32,000 – £60,000 | £40,000 – £90,000 |
| Year 2 | £22,000 – £38,000 | £10,000 – £25,000 |
| Year 3 | £23,000 – £40,000 | £10,000 – £25,000 |
| Three-year total | £77,000 – £138,000 | £60,000 – £140,000 |
ISO 27001 is more expensive in year 1 and materially cheaper in years 2 and 3 because of the surveillance-audit model. SOC 2 is cheaper in year 1 but runs a full re-audit annually. Over three years the totals are similar; the cash-flow shape is different.
The ISO 27001 side of this calculation, with its three-year certification cycle and UK-leaning audit-fee bands, is broken down at iso27001certificationcost.com. Roughly 80 percent of the SOC 2 Common Criteria control set maps directly onto ISO 27001 Annex A, which is why teams running both standards concurrently typically save 30 to 40 percent on the combined engagement.
The bundled cost math
Concurrent SOC 2 plus ISO 27001 audit programmes typically save 30 to 40 percent vs sequential. The saving comes from four sources.
Shared evidence base. Access reviews, change tickets, vendor reviews, and incident response logs are collected once and tested against both frameworks. Roughly 80 percent of the evidence population is shared.
Shared readiness. One readiness workstream covers both control sets. The gap log identifies framework-specific items, but the core work is shared.
Dual-purpose policies. Information security policy, access management policy, change management policy, incident response policy, and vendor management policy are written once and apply across both frameworks. Avoid framework-specific policy splits.
Single auditor relationship. Where the firm is dual-accredited (UKAS for ISO 27001, AICPA for SOC 2), one engagement letter, one project manager, one evidence portal. Where the firms differ, the saving is harder to capture.
Which first
| Customer base | Recommended sequence | Why |
|---|---|---|
| US-leaning enterprise SaaS | SOC 2 first, ISO 27001 in year 2 or 3 | SOC 2 is the dominant signal in US procurement. ISO 27001 follows once international expansion is real. |
| EU/UK-leaning B2B | ISO 27001 first, SOC 2 in year 2 | ISO 27001 is the structured ISMS expectation. SOC 2 follows for US customer expansion. |
| Both within 12 months | Concurrent | Maximum saving from shared engagement. Requires a dual-accredited firm and a unified readiness workstream. |
| Regulated industry (fintech, healthtech) | Often both, sequencing customer-led | Customer contracts force the order. Plan the multi-year programme up front. |
Try the sequencer
The tool below shows the 24-month and 36-month combined cost under each path. The concurrent path applies the shared-engagement saving; sequential paths assume separate engagements.
Cross-reference
For the timeline shape on the SOC 2 side, see the timeline page. For the audit-firm tier that supports dual-accreditation, see the audit firm fees page. For the GRC platform decision in a multi-framework programme, see the GRC platforms page.