When does custom software have better 3-year TCO than SaaS?

Custom typically wins on TCO when: SaaS per-user pricing scales with your team growth (a 50-person team at £50/user/month = £30,000/year), SaaS add-ons and integration costs accumulate (common to double the base price in year 2–3), or the SaaS product requires significant customisation (implementation fees). Rule of thumb: if 3-year SaaS cost exceeds £60,000–£80,000, custom is worth serious evaluation.

Can a SaaS product meet FCA or DTAC compliance requirements?

Some can, some cannot. For FCA Consumer Duty: some SaaS FinTech products are designed with FCA compliance in mind — check carefully. For NHS DTAC Domain 2 (Data Protection): requires evidence of UK GDPR compliance, UK data residency, and a signed DPA — many SaaS products have US data residency by default. For GDS Service Standard: off-the-shelf products often cannot satisfy all 18 points, particularly open source and accessibility requirements.

What UK GDPR checks should I do before buying SaaS?

Data residency: are data centres in the UK or EEA? US-based SaaS: is there a UK-EU adequacy agreement or IDTA for transfers? Data Processing Agreement: does the vendor have a UK GDPR Article 28 DPA? Sub-processors: are all sub-processors listed and adequate for UK transfers? Right to erasure: can the vendor technically support UK GDPR erasure requests for your data?

Custom Software Vs Saas Uk

Custom Software vs SaaS — Honest Decision Framework for UK Businesses (2025)

Updated: June 20259 min read

🇬🇧 UK Market💷 GBP⚖️ UK Law🔒 UK GDPR📊 Comparison

Direct Answer

SaaS wins when: the software is not your competitive advantage, an off-the-shelf product meets 80%+ of your requirements, and your UK GDPR requirements are standard. Custom wins when: the software IS your competitive advantage, SaaS cannot meet UK regulatory requirements (DTAC, FCA, GDS), or 3-year SaaS TCO exceeds the custom build cost. ClickMasters will tell you honestly which is right. The custom vs SaaS decision is one of the most consequential UK software strategy choices. Made wrongly, it leads to: years of SaaS lock-in at increasing cost, or expensive custom builds for functionality a SaaS product already does well. Here is an honest framework based on real UK market experience.

Factor	Custom Software	SaaS Product
Competitive differentiation	✅ Your moat — competitors cannot easily replicate	❌ Competitors have the same product
Time to first value	4–20 weeks (slower)	Days to weeks (faster)
Initial cost	£12,000–£200,000+	Low/zero upfront
3-year total cost	Fixed + maintenance	Rising: licence + per-user + add-ons
UK regulatory compliance	✅ Fully tailored (DTAC, FCA, GDS)	⚠️ May not meet specific UK requirements
Data control and residency	✅ Complete — AWS eu-west-2 by default	⚠️ Check DPA and data residency
Scalability	Designed to your growth trajectory	Vendor manages — but pricing scales up
Integration flexibility	✅ Full — you own the API	Limited to vendor integrations
IP ownership	✅ 100% yours	❌ You license, not own
Vendor dependency	None	High — switching cost can be enormous
UK GDPR control	✅ Article 25 by design	Depends on vendor DPA quality