Oct 21
The risks of legacy accounting systems rarely begin with a sudden failure. They appear as filing gaps, security weaknesses, administration and outdated figures. From 1 April 2028, Companies House will require commercial software for accounts filings, so businesses relying on its web or paper accounts services must prepare. The government also plans mandatory electronic VAT invoicing for business transactions from April 2029. Unsupported software risks data breaches; manual processes waste time. Replacing a system before it becomes a compliance or security problem usually gives a business more control over cost and disruption. Review support dates, data backups and connections to other essential applications before replacement.
The main risks are incompatible filing, cyber vulnerabilities, manual errors, delayed reporting, weak audit trails and unreliable evidence for lenders or buyers. Reliance on one employee also risks disruption. These problems often accumulate before directors recognise their financial impact.
Legacy does not automatically mean old. An older package can work well if supported, secure and compliant. The concern is an obsolete, poorly maintained or inflexible system that forces staff to compensate for its limitations through spreadsheets and manual work.
UK businesses face several confirmed digital reporting deadlines.
| What they look at | What they want to see | How to prepare |
|---|---|---|
| Cash flow cover | Comfortable headroom for all scheduled debt payments | Cash flow forecast and realistic downside tests |
| Quality of earnings | Repeatable profit, not temporary gains or aggressive adjustments | Normalised accounts and supporting evidence |
| Management team | Ability to lead without relying on the seller | Experience, responsibilities and succession plans |
| Your own money | Genuine financial commitment | Proof of funds and equity structure |
| Customers and suppliers | Manageable concentration and secure commercial relationships | Contract review and concentration analysis |
| Security | Assets and rights capable of supporting the facility | Asset register, valuations and security review |
| Working capital | Cash available for operations after completion | Detailed opening balance and working capital model |
| Tax and compliance | Reliable reporting and manageable liabilities | Current filings, HMRC position and tax due diligence |
Companies House has confirmed that from 1 April 2028 companies must file annual accounts using commercial software, whether they submit them themselves or through an accountant. Accounts web and paper filing will close; other online services remain. Accounts software must produce the necessary iXBRL information. The earlier proposed April 2027 deadline has been replaced.
Making Tax Digital for Income Tax applies to qualifying sole traders and landlords with relevant gross income above £50,000 from April 2026, £30,000 from April 2027 and £20,000 from April 2028. This is based on qualifying income rather than profit. Directors with such income may need separate compatible software.
For invoicing, the government’s consultation response sets out mandatory electronic VAT invoices for business-to-business and business-to-government transactions from April 2029. Standards are pending, with a roadmap due at Budget 2026. Our article on business tax changes to watch in the Autumn Budget covers upcoming announcements. An emailed PDF may not meet the future rules.
Accounting systems hold bank details, supplier accounts, personal information and often payroll records. Unsupported operating systems and applications no longer receive routine security patches, leaving vulnerabilities open to attackers. The NCSC says the only fully effective way to deal with obsolete products is to stop using them. It recommends considering cloud services. Standard Windows 10 support ended on 14 October 2025; extended security programmes remain available.
The government’s Cyber Security Breaches Survey 2025/26 reported that 43% of UK businesses identified a cyber security breach or attack in the previous 12 months, including 46% of small businesses. Phishing remained the most commonly identified type. These concern cyber incidents generally, not accounting software alone. Employee awareness and secure payment approval procedures remain important additional safeguards.
Older systems can involve repeated spreadsheet exports, duplicate entry, emailed approvals and manual invoice matching. They create avoidable work and mistakes. Measure errors, duplicate invoices and time spent reconciling transactions. Track these activities for several weeks to build a useful comparison.
For example, ten hours of weekly re-keying at an employment cost of £20 an hour represents £10,400 over 52 weeks, excluding error correction and lost opportunities. That is illustrative. Compare it with migration, subscription, training and support costs.
If month-end reporting takes three weeks, managers may discover margin problems, overdue debtors or increasing expenditure too late to respond. Modern systems can produce more timely management accounts, when records are accurate. This helps owners monitor key financial KPIs and maintain a 13 week cash flow forecast without assembling spreadsheets.
Better customer ageing reports and scheduled reminders also support control of late payments. Visibility over tax balances can reduce surprises, as discussed in our guide to HMRC VAT and PAYE direct debits and cash flow. Automation still requires checks.
Older packages may lack permissions, audit logs and approval workflows. That can make unauthorised amendments harder to identify and errors harder to investigate. Cloud software also requires proper controls. Where irregularities are suspected, forensic accountants and investigations specialists can help establish what happened. Strong approvals and audit trails help prevent losses.
Lenders and prospective buyers expect financial information they can reconcile to supporting transactions. Incomplete ledgers, slow reporting and inconsistent figures can delay due diligence, complicate credit decisions and undermine valuations. Our guide to SME lending and funding for growth explains the evidence financiers may request. If an external audit is needed, clean records and traceable adjustments generally make the process more efficient. Software cannot replace sound controls.
A system maintained by one bookkeeper on a single computer creates a continuity risk. Staff absence or hardware failure could interrupt reporting. Cloud services can improve access and resilience with appropriate backups and permissions. Test data exports and recovery.
Cross-border organisations must manage sterling and euro transactions, different VAT rules and intercompany balances. Manual spreadsheets can make exchange differences and reconciliations difficult to track. Our guide to sterling and euro books and article on setting up a company in both the UK and Ireland explain the practical considerations. Specialist cross-border accounting and tax advice can help identify suitable reporting and integration requirements.
Plan the transition before buying software. Our guide to switching to cloud accounting covers the wider process.
Migration has upfront costs and can temporarily reduce productivity. Consider subscriptions, implementation work, training and necessary hardware alongside available cash. Use our guide to reforecasting for interest rates and inflation to test the business case under alternative borrowing and cost assumptions.
Where inaccurate ledgers coincide with overdue filings or cash shortages, correct the underlying records before relying on automated reports. Our guide to financial distress warning signs helps identify urgent problems, while HMRC tax debt should be addressed promptly. Recovery accountants can help improve cash flow; for otherwise viable businesses with serious creditor pressure, a company voluntary arrangement may provide a structured restructuring option.
It is a system that has become difficult to maintain, integrate or secure, or that no longer supports necessary reporting. Age alone does not determine whether software is fit for purpose.
From 1 April 2028, Companies House will require annual accounts to be submitted using commercial filing software. Businesses may use their own software or appoint an accountant with a suitable solution.
A reputable provider may offer encryption, backups and access controls, but security also depends on user permissions, updates and recovery procedures. Use multi-factor authentication and review supplier arrangements. The business remains responsible for protecting its information.
The government plans mandatory structured electronic VAT invoicing for business-to-business and business-to-government transactions from April 2029. An implementation roadmap is due at Budget 2026.
If you are concerned that your systems cannot support future filing, secure your records or deliver timely reports, SCC can review the current arrangements and plan a proportionate migration. Contact your nearest office at SCC Chartered Accountants to discuss a suitable approach before existing software becomes a constraint.
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