IT providers for professional services firms

There are 370 IT providers serving Professional Services clients listed in the Assurix directory, including 11 with verified Assurix trustmarks.

Last updated: 14 November 2026

Accountants, consultancies, architects, recruiters and agencies all sit somewhere inside a client's supply chain. When a bigger client checks who they work with, your IT provider's security can become part of that conversation.

There are providers listed here that work with professional services firms. Providers carrying the Assurix Trusted MSP badge are shown first, and any working toward it appear as On the Journey. The rest are shown as not yet Assurix-verified, which is a neutral label and includes plenty of capable, established providers.

Below, you'll find what a good provider should be able to show a firm like yours, the questions worth asking, and how independent verification of a provider's controls can become something you pass on to a client.

What to look for in a provider for your firm

These firms sit inside their clients' supply chains, so an IT provider's evidence often ends up in front of a client. Here's what to look for.

Care with client access
Many firms reach into client systems, and accountants use HMRC agent services on their clients' behalf. That's a lot of trust in one place. Ask how a provider protects those connections and controls who on its side can use them.
Defences against invoice fraud
Where you handle client payments or payroll, business email compromise and invoice fraud are recognised risks. Ask how a provider helps spot a spoofed supplier email or a fake change of bank details. The firm carries the loss if a payment goes to the wrong place.
Answers for client security questions
Larger clients often send security questionnaires before awarding work. A provider that can evidence its own controls gives you concrete answers for the sections about IT. Ask what documentation or verification it can hand you.
Fit with contract clauses
Client contracts increasingly include security schedules and audit or assurance clauses. Your provider's setup often decides whether you can meet them. Ask how it helps you satisfy these clauses, and what it can evidence if a client wants to check.
Proof you can pass on
As a supplier in someone else's chain, the evidence you can show matters. Look for a provider that holds independent verification of its controls, so you can pass that proof to a client who asks. Continuous, independent verification carries more weight than a self-description.

Questions to ask an IT provider

Ask these with your own client contracts and questionnaires in mind. The answers tell you how much of that work your provider can support.

  1. How do you protect the client systems and HMRC agent access we use on our clients' behalf? Access to client environments is a high-value target and a high-trust responsibility.
  2. What controls do you have against invoice and payment fraud where we handle client money or payroll? Business email compromise targets firms that move money for others.
  3. Can you help us complete the security questionnaires our larger clients send? Winning work increasingly depends on answering these well.
  4. How do you help us meet the security schedules and audit clauses in our client contracts? These clauses are appearing in more contracts and carry real obligations.
  5. How is our clients' data separated and protected across the accounts you manage? Confidential client information sits under UK GDPR.
  6. Do you hold independent verification of your own security? Independent proof is something you can pass straight to a client who asks.

IT providers serving Professional Services

Why security follows these firms up the chain

Professional services covers a wide group: accountants, consultancies, architects, recruiters, agencies and similar firms. What many share is access to their clients' world. Accountancy firms, for example, reach into client systems and HMRC agent services on their clients' behalf, which is a high level of trust to hold.

Where firms handle client payments or payroll, business email compromise and invoice fraud are recognised risks. Someone posing as a supplier or a colleague can redirect a payment, and the firm carries the fallout.

There's also pressure coming down the contract chain. Client contracts increasingly include security schedules and audit or assurance clauses. And many of these firms are themselves asked to complete security questionnaires by larger clients before they win work. In each case, your IT provider's security becomes part of what you can show. Independent evidence of that provider's controls is something you can hand to a client who asks.

How the Assurix Trustmark helps your firm

When a larger client sends you a security questionnaire, your IT provider's controls are part of your answer. A Trusted MSP has passed all 59 Assurix controls, aligned to the NCSC Cyber Assessment Framework v4, with continuous monitoring and a yearly reassessment. If something slips, the provider gets 30 days before the badge is publicly suspended. That's independent proof you can pass to a client, sitting behind your own security promises.

Frequently asked questions

We keep getting security questionnaires from clients. How does our IT provider help?

Larger clients often ask suppliers to complete a security questionnaire before awarding work, and a lot of the questions land on how your IT is run. If your provider can evidence its own controls, you can answer with something concrete instead of a best guess. Independent verification, like the Assurix Trusted MSP badge, gives you a reference point you can pass straight through. It won't fill in every answer for you, but it removes a lot of the uncertainty from the security section.

What does 'Assurix Verified' actually verify?

It verifies that an IT provider has passed all 59 controls in the Assurix assessment, aligned to the NCSC Cyber Assessment Framework. Passing means all 59, with no partial credit. Assurix then keeps checking through continuous monitoring and reassesses each year, so the Trusted MSP badge reflects current standing. If a control fails, there's a 30-day window to fix it, after which the badge is publicly suspended and drops off the listing. For a firm that answers to clients, that's independent proof about the provider, checked by a third party.

What does 'On the Journey' mean when I'm comparing providers?

It means the provider is working toward the Assurix Trustmark and hasn't passed the full assessment yet. The status is capped at six months, so it shows a provider is actively putting the work in within a fixed window. When you're comparing providers, treat it as a sign of intent and momentum. A Trusted MSP has already cleared all 59 controls, while an On the Journey provider is on the way there and working to a deadline.

Is a provider without an Assurix status less safe for our firm?

No. A provider listed as not yet Assurix-verified has simply not been through the assessment. Plenty are strong, well-run firms, and some hold their own security certifications. The label carries no judgement. Treat it as your cue to ask the questions on this page and look at whatever evidence a provider can show, from certifications to references, before you decide.

Does the Trustmark get our firm Cyber Essentials or ISO 27001?

No. The Assurix Trustmark is not a certification you can pass on, and it doesn't grant Cyber Essentials, ISO 27001 or SOC 2. Those are separate schemes a provider earns in their own right, and a client might ask about them directly. What Assurix gives is independent, ongoing verification of a provider's controls against the NCSC Cyber Assessment Framework. A provider can hold its own certifications and the Trusted MSP badge together, and each answers a slightly different question.

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