A complaint arrives, a manager wants immediate action and everybody already has an opinion. That is when a workplace investigation needs structure. Its purpose is not to prove guilt. It is to establish the relevant facts, test reasonable evidence from all sides and decide whether there is a case to answer. For SMEs across the Tees Valley and wider North East, the following seven-step process provides a practical starting point.
1. Decide what needs investigating
Write a neutral description of the concern. Identify the alleged conduct, relevant dates, people, rules and questions to answer. Avoid language that assumes the outcome. ‘Did the employee falsify the inspection record?’ is a question; ‘investigate the falsified record’ treats the allegation as fact.
Check whether the matter is really disciplinary. Unclear training, a health condition, a safety concern raised by a worker or a complaint about another person may require a different or joined-up process. Do not force every problem into misconduct.
Related guide: when an employee discloses a health condition →
2. Apply the current Acas Code—not a draft
The current Acas Code says employers should investigate promptly, tell the employee the basis of the problem, allow a proper response and provide an appeal against formal action. The investigation should fit the circumstances; admitted timekeeping will not need the same exercise as alleged fraud, harassment or a serious safety breach.
Acas published a draft replacement Code for consultation on 30 July 2026, with consultation open until 23 September 2026. That draft is not yet in force. Employers should continue to follow the current 2015 Code and their own procedure, while recognising that guidance may change after the consultation and approval process.
Failing to follow the Code is not automatically unlawful, but a tribunal can adjust compensation by up to 25% for unreasonable non-compliance where a relevant claim succeeds. Section 98 of the Employment Rights Act 1996 also makes the employer’s reason and overall reasonableness central to a fair dismissal.
Acas: current disciplinary and grievance Code ↗ · Acas: draft Code consultation ↗
3. Choose an impartial investigator and set a proportionate plan
Choose somebody who can approach the evidence with an open mind and has the time and competence to complete the work. Where practicable, use a different person to chair any later disciplinary hearing. Small employers should record how fairness will be protected and consider external support for senior, sensitive or complex allegations.
Plan the allegation, witnesses, documents, digital evidence, interview order, confidentiality, timescale and updates. Test the issue without searching for unrelated faults. If credible new concerns emerge, formally revise the scope.
4. Preserve evidence before it disappears
Secure relevant records early: emails, messages, rotas, access logs, CCTV, training records, policies and equipment data. Preserve original material and record its source. Do not ask witnesses to create a shared account or edit statements until they match.
Collect only relevant information and handle it confidentially. Follow privacy notices, retention arrangements and monitoring policies. If criminal conduct, safeguarding, whistleblowing, regulatory reporting or serious safety risk may be involved, take advice before an internal step compromises another process.
Related guide: preventing and responding to workplace sexual harassment →
Get the investigation scope right before interviews begin.
HR + SAFETY can help define the allegations, identify proportionate evidence and build a fair investigation plan before early mistakes narrow or compromise the process.
Discuss a workplace investigation5. Interview to understand—not to prosecute
Use open questions and let each person explain what they saw, heard, did or understood. Test timing, location, sequence, source of knowledge and inconsistencies. Separate observation from assumption or rumour, and ask what evidence may confirm or challenge the account.
Explain the meeting’s purpose, how notes will be used and the expectation of confidentiality. Let the interviewee check and comment on the notes. There is no general statutory right to be accompanied at a disciplinary investigation meeting, although a policy, reasonable adjustment or fairness may justify it. The statutory right normally applies at the later disciplinary hearing.
Do not promise complete secrecy. Information may need to be shared so the allegation can be answered fairly. Where a witness asks for anonymity, explore the reason, weigh the evidence carefully and take advice before relying materially on an account the employee cannot properly challenge.
Acas: carrying out an investigation ↗ · Acas: investigation meetings ↗
6. Treat suspension as a risk control, not a punishment
Suspension should not be automatic. Consider the actual risk of interference with evidence, influence over witnesses, repetition, danger or an unworkable workplace breakdown. First consider changed duties, location, reporting line, access permissions or working arrangements.
If suspension is necessary, keep it brief, normally maintain pay, explain that it is neutral and review it regularly. Plan contact and support during the absence.
7. Report the evidence and keep the decision separate
The report should set out the allegation, scope, steps, evidence, material conflicts, established facts and limitations. It can recommend no further action, informal action or a disciplinary hearing. It should not decide the sanction unless the procedure combines roles and fair separation was genuinely impracticable.
Use a practical threshold: is there a case to answer based on the evidence available? That is not the same as deciding guilt. If the matter proceeds, give the employee the allegations and relevant evidence in enough detail and time to prepare for the disciplinary hearing. The hearing manager must consider the response with an open mind.
Tell relevant people when the investigation has finished, while protecting confidential details. Record wider lessons such as unclear rules, weak supervision, missing training or unsafe systems, and assign those improvements separately.
Acas: what happens after an investigation ↗ · Related guide: unfair dismissal changes in 2027 →
Workplace investigation checklist for managers
For serious, technical or sensitive cases, pause before making avoidable commitments. A focused external review at the start is often quicker and safer than trying to repair an investigation after the scope, evidence or communications have gone wrong.
- Define each allegation in neutral, specific language.
- Check the correct policy and whether another process also applies.
- Appoint an investigator who can act objectively.
- Set scope, evidence sources, witnesses and a realistic timescale.
- Preserve relevant documents and digital material lawfully.
- Seek evidence that supports and challenges the allegation.
- Keep suspension exceptional, justified and under review.
- Give interviewees a fair chance to check meeting notes.
- Explain evidential conflicts and limitations in the report.
- Keep the case-to-answer decision separate from any sanction.
Workplace investigation support across the North East
HR + SAFETY supports SMEs in Stockton-on-Tees, Middlesbrough, Hartlepool, Darlington, County Durham, Sunderland, Gateshead, Newcastle, Northumberland and across the wider North East. We can help frame allegations, plan or conduct an investigation, prepare questions, review evidence and support the handover into a fair disciplinary decision.
Where the issue involves a workplace accident, unsafe act, competence concern or health condition, our joined-up HR and safety approach helps the employer examine the management system without confusing a safety investigation with a disciplinary case. The output is a clearer evidence trail, a fairer decision and practical actions beyond the individual allegation.
Investigate to establish the facts, not to justify a decision already made. Define the allegation, preserve relevant evidence, hear reasonable accounts, keep suspension exceptional and produce a balanced report that lets a separate decision-maker assess whether there is a case to answer.
This guide provides general information for UK employers. It is not legal advice and should not replace advice based on the facts of a specific matter.