When HMRC’s online services go down, everything slows – filings, VAT returns, payroll adjustments and client updates. We have seen several periods of planned downtime in 2025, including over the late-May bank holiday and additional maintenance in September (HMRC service availability). While these windows are announced, they still create pressure near deadlines and expose weak points in how businesses process tax and finance data. At the same time, cyber threats continue to bite: just over four in ten UK businesses reported a cyber breach or attack in the past 12 months (Cyber Security Breaches Survey 2025). Put together, service outages and rising cyber risk make one thing clear – cyber resilience for finance systems is now a business essential, not a nice-to-have.
Resilience is about how quickly you can keep operating and recover, not just how you prevent incidents. That means robust backups, layered access controls, tested disaster-recovery steps, and clear playbooks for staff. It also means planning around third-party systems we all rely on – HMRC gateways, banking feeds, payroll portals and cloud accounting platforms. Below we share practical steps we use with clients to strengthen cyber resilience for finance systems, so finance keeps moving even when services wobble.
Build a practical backup routine that actually restores
Backups only help if you can restore data quickly. For finance teams using cloud software, mix in platform exports with independent storage. Aim for both versioned cloud backups and periodic offline copies.
- Scope and frequency: Daily core ledgers, weekly document stores. Month-end full snapshots.
- Independence: Keep at least one copy outside your primary cloud, using separate credentials.
- Restoration tests: Quarterly restores into a sandbox to confirm completeness and timestamps.
- Retention policy: Keep monthly snapshots for 12 months – longer if your sector requires it.
Two quick wins for cyber resilience for finance systems: schedule automatic CSV exports of key ledgers, and maintain a read-only “cold” backup of supplier and payroll bank details. If ransomware or account lockout strikes, you still have the critical data to pay staff and suppliers.
Enforce two-factor authentication everywhere
Weak or reused passwords remain the common entry point. Turn on 2-step verification across HMRC, banking, email and accounting apps. HMRC supports 2-step verification for developer and user access flows, and the National Cyber Security Centre recommends enabling 2SV wherever available (HMRC 2-step verification; NCSC guidance). For administrators, enforce app-based authenticators rather than SMS where possible, and store recovery codes in a sealed process where two people must authorise access.
Use these controls to tighten cyber resilience for finance systems:
- Role-based access: Minimum permissions for each finance role – reviewers do not need payment rights.
- Leaver process: Access reviews on every staff change, with immediate removal of dormant accounts.
- Shared mailboxes: Require 2SV and audit who can send from certain addresses.
Plan for service outages before the deadline crunch
Outages happen – planned, and sometimes unplanned. HMRC publishes availability updates and maintenance windows; use them to time submissions and maintain buffers. Build a short, written playbook for each core finance process and include the “offline” route.
- Self assessment submissions: Finalise and submit at least five working days before cut-offs. If the service is unavailable, store a timestamped PDF and XML export and retry once services resume.
- PAYE and RTI: Keep a manual spreadsheet template for emergency gross-to-net and net-to-gross checks. Process payments via secure bank import files when your payroll portal is down; submit RTI as soon as access returns.
- VAT returns: Hold a read-only MTD bridging template. If your API agent is unavailable, ensure you can export the nine-box summary from your accounting system and submit when HMRC is back online.
These steps turn service blips into minor delays, not operational stoppages, strengthening cyber resilience for finance systems under real-world pressure.
Test disaster-recovery timings, not just checklists
Disaster-recovery documents often sit in folders, untested. Replace tick-boxes with time targets and drills.
- Recovery time objective (RTO): How fast you need ledgers, payroll and banking approvals back online.
- Recovery point objective (RPO): How much data loss you can tolerate – for finance data, aim for hours, not days.
- Table-top exercises: Twice a year, rehearse a ransomware or outage scenario. Assign roles: incident lead, communications, technical recovery, and approvals.
- Supplier escalation: Keep named contact routes for your key vendors and note their published SLAs.
Link this to your current trading picture. Lower growth this year means cash buffers are tighter for many firms – the OBR’s March 2025 outlook projects real GDP growth of about 1.0% in 2025, down from 2.0% assumed in October (OBR, March 2025). Faster recovery matters because downtime directly drags cash collection and increases admin hours. Clear, tested timings are the backbone of cyber resilience for finance systems.
Control payment risk at source
Most finance losses come from business email compromise, invoice fraud and payroll redirections rather than Hollywood-style hacks. A few simple, repeatable controls make a difference.
- Supplier changes: Bank detail changes require a call-back to a verified number – never the number on the new invoice.
- Payment runs: Dual approval in banking and in your accounting system. Rotate the second approver.
- Email rules: Block auto-forwarding from finance mailboxes and alert on new forwarding rules.
- Data minimisation: Remove bank details from PDFs shared with external partners where not needed.
These are small steps with big impact on cyber resilience for finance systems, especially for SMEs without large IT teams.
Train people and measure behaviour
Phishing remains the top attack route (Cyber Security Breaches Survey 2025). Short, quarterly refreshers beat long, infrequent courses. Keep it realistic:
- Phish drills: Simple simulations with instant micro-lessons when someone clicks.
- Just-in-time prompts: Banner warnings on external emails and payment requests over a set amount.
- Clear reporting: One button to report suspicious emails to IT or your outsourced provider.
Back up training with visible leadership. The finance lead should approve controls and communicate why they matter. Culture is a major lever in cyber resilience for finance systems.
Keep a simple incident playbook and share it
When something feels off – strange login prompts, missing data, locked files – speed matters.
- Immediate steps: Disconnect affected devices from the network, preserve logs, and notify your incident lead.
- Evidence capture: Screenshots, timestamps, affected systems, user accounts – stored in a secure folder.
- Regulatory considerations: Assess data exposure. If personal data is involved, consider ICO reporting timelines.
- External support: Keep details for your cyber insurer and IT partner to hand.
Publish the playbook in a shared location and print one copy in the finance office. That accessibility is part of cyber resilience for finance systems when screens or accounts are unavailable.
We can design finance processes to absorb shocks – planned HMRC downtime, API hiccups, supplier outages and the steady drumbeat of phishing attempts. The government’s own data shows 43% of businesses reported a breach or attack in the last year, and the economic backdrop leaves little room for avoidable disruption. The right response is practical: strong backups, mandatory 2SV, clear approvals, and tested recovery steps.
If you would like us to review your controls and create a short, usable playbook for cyber resilience for finance systems, get in touch and we’ll map out quick wins for your team.
