A Jamie HR manager's guide

The manager's guide to the 2027 flexible working reasonableness test

A practical guide for managers and SMEs on preparing for the flexible working reasonableness test added by the Employment Rights Act 2025: what it changes, what is already confirmed, what remains unsettled, and how to prepare your refusal practice now.
Reasonableness test
2027, date not fixed
Evidence, not just labels

Refusing a flexible working request is about to require more than citing a reason.

The Employment Rights Act 2025 adds a reasonableness test to how a flexible working request can be refused. This guide focuses on that change alone, not the wider request process covered in our companion guide, setting out what the law now says, what is confirmed, and how to prepare your refusal practice before it takes effect.

What's inside
Where refusals stand today3
What the Employment Rights Act 2025 adds4
What a refusal will need to state5
Is a written explanation required?6
What's confirmed on timing7
What is genuinely still unsettled8
Document the real reasoning, not just the category9
Apply the same standard consistently10
Review your past refusal practice11
Getting ready for 2027: the essentials12
How Jamie HR helps13

Where refusals stand today

Before this change takes effect, a refusal only has to fit one of eight specified reasons.
  • An employer can currently refuse a flexible working request only for one of eight reasons specified in law, such as extra cost, an inability to reorganise work, or a detrimental effect on customer demand.
  • Citing one of those eight reasons is currently sufficient. There is no separate statutory test requiring the employer to explain why relying on that reason is reasonable.
  • The employer must still consult the employee before refusing and communicate the decision within the statutory two-month period, under the existing framework.

What the Employment Rights Act 2025 adds

Section 9 of the Employment Rights Act 2025 inserts a reasonableness test into the existing refusal framework.
  • The refusal test becomes two-part: the employer must still rely on one of the eight specified grounds, and it must be reasonable for the employer to refuse the request on that ground.
  • This does not create a new list of reasons or a right to flexible working. It adds a second hurdle on top of the existing eight grounds.
  • The change is made by inserting new subsections into section 80G of the Employment Rights Act 1996, the section that already sets out the flexible working framework.
  • The Employment Rights Act 2025 received Royal Assent on 18 December 2025.
Manager tip
The eight grounds and the two-month timescale are not changing. What is new is the extra requirement to show the refusal itself was reasonable, so treat this as an addition to your existing process, not a replacement for it.

What a refusal will need to state

The Act sets out what the employer's notification of a refusal must contain once the change is in force.
  • The notification refusing a request must state the ground or grounds relied on from the list of eight specified reasons.
  • It must also explain why the employer considers it reasonable to refuse the request on that ground.
  • A notification that names one of the eight grounds without explaining why refusing on that ground is reasonable will not meet the new requirement.
  • The detail of how employers are expected to comply, described in the Act as steps an employer must take, is left to regulations still to be made by the Secretary of State.

Is a written explanation required?

The Act itself does not say the explanation has to be in writing.
  • The existing law requires the employer to notify the employee of the decision, but does not specify that the notification must be in writing.
  • The Act's new wording requires the ground and the explanation to be part of that notification, again without specifying a written format in the primary legislation.
  • The government consultation on the process for consulting employees, which closed on 30 April 2026, asked whether employers should be required to communicate the outcome of the consultation meeting and the decision in writing.
  • Until that question is settled, a written explanation is good practice rather than a confirmed statutory requirement. Put one in writing anyway, so your process already meets the higher standard once it applies.
Watch out
Do not assume an oral explanation naming a business reason will be enough once the reasonableness test applies. Confirm the reasoning in writing so there is a clear record if the decision is ever challenged.

What's confirmed on timing

Part of this change is already in force in a technical sense; the duty that affects a manager's decision is not.
  • Section 9 of the Employment Rights Act 2025 came into force on 6 January 2026, but only for the purpose of letting the Secretary of State make regulations under the flexible working provisions.
  • The reasonableness requirement itself, the duty that will actually apply when a manager refuses a request, is not yet in force.
  • The government's factsheet on the Act states these changes will take effect in 2027, without giving an exact date.
  • ACAS confirms the government has not announced when in 2027 most Employment Rights Act 2025 changes, including this one, will happen.

What is genuinely still unsettled

Be plain about what is confirmed law and what is still to be decided.
  • The exact 2027 commencement date has not been fixed and will be set by further commencement regulations.
  • The detailed process for consulting employees before a refusal, including any requirement to give the outcome in writing, was the subject of a government consultation that closed on 30 April 2026. No government response had been published as of the date this guide was checked.
  • What 'reasonable' means in practice for a given refusal is not defined in the Act itself, and is likely to be shaped over time by ACAS guidance and, in due course, tribunal decisions.
  • Treat any specific description of what will count as reasonable, beyond the two-part test itself, as anticipated rather than settled law until that detail is published.

Document the real reasoning, not just the category

Preparing now means changing what sits behind a refusal, not only how it is worded.
  • Record the actual evidence behind a refusal, such as the specific costs involved, the staffing gap identified, or the customer impact assessed, rather than only naming which of the eight grounds applies.
  • Keep that evidence from the point the request is considered, not reconstructed afterwards if the decision is later questioned.
  • Where a request is only partly refused, or a modified version or trial period is offered instead, record the reasoning for that alternative in the same way.
  • Set out this expectation in your flexible working policy, so every manager knows that naming a ground alone will not be enough once the reasonableness test applies.
Manager tip
Start keeping this evidence now, well ahead of 2027. A file of dated notes covering the actual business impact behind a refusal is far easier to build at the time than to reconstruct later.

Apply the same standard consistently

A reasonable refusal is easier to stand behind if similar requests are handled the same way.
  • Compare a new refusal against how similar requests have been handled in the same team or role, and be able to point to the reason for any difference in outcome.
  • Brief every manager who considers requests on the eight grounds and on what business evidence for relying on each one needs to look like.
  • Where a request is refused for one employee but a similar request was previously granted for another, record the factor that distinguishes the two decisions.
  • Apply the ACAS Code of Practice's consultation requirements to every request in the same way, regardless of the outcome you expect to reach.

Review your past refusal practice

Look back before the reasonableness test takes effect, not after.
  • Pull together the flexible working refusals made over the last year or two and check whether the business evidence behind each one is recorded, or only the ground relied on.
  • Identify any pattern of refusing similar requests on the same ground without evidence recorded for each individual case.
  • Update your flexible working policy and manager guidance now to require the fuller reasoning this guide sets out, ahead of the 2027 commencement date.
  • Where gaps are found, use them as a training point for the managers involved.

Getting ready for 2027: the essentials

A summary of the essentials covered in this guide:
  • From 2027, exact date not yet confirmed, a refusal will need to rely on one of the eight specified grounds and explain why relying on it is reasonable.
  • The Act itself does not mandate a written explanation. Put one in writing anyway as good practice, ahead of any further requirement the ongoing consultation may bring.
  • The exact commencement date and the wider process for consulting employees remain unconfirmed, so revisit this guide once the government publishes its response and any commencement regulations.
  • Record the actual business evidence behind every refusal, apply the same standard consistently across similar requests, and review your recent refusal decisions now.

How Jamie HR helps

Jamie HR keeps the ground relied on, the reasoning behind it and every consultation note together against each flexible working decision.
  • Flexible working requests logged with the ground relied on and the business reasoning recorded against each decision.
  • Consultation and decision notes stored against each request, ready if a refusal is ever challenged.
  • Policy library so every manager applies the same reasoning standard to similar requests.
  • Guidance kept current as the government publishes its consultation response and commencement date for the reasonableness test.
Start a Free Trial
jamiehr.com
This guide is general information, accurate to the best of our knowledge as of 2026, and is not legal advice. Employment law changes and every situation is different, so for a specific case take professional HR or legal advice. Sources: gov.uk, legislation.gov.uk, ACAS and the Employment Rights Act 2025.