Challenge CMS Decisions: A Guide for Parents

Important: Children Act 1989 and CMS Decisions

The Children Act 1989 is central to family-court decisions about children's welfare, but it is not the statutory formula that CMS uses to calculate maintenance. For CMS itself, the more direct welfare provision is section 2 of the Child Support Act 1991 when discretionary powers are exercised. Avoid presenting the Children Act welfare principle as though it lets CMS disregard the maintenance formula.

Important: Public-Law and Human-Rights Arguments Need Care

Wednesbury irrationality has a high threshold. Article 8 and Article 1 of Protocol 1 may be relevant in an appropriate case, but the existence of financial hardship or fluctuating income does not by itself establish a Human Rights Act breach. Where an ordinary statutory MR or tribunal appeal is available, the strongest first argument is normally the specific calculation/evidence error. Public-law and Convention arguments are usually supplementary and specialist legal advice may be appropriate.

Relevant Legislation

Child Support Act 1991

The Child Support Act 1991

established the statutory child

maintenance scheme and provides the legal basis for child maintenance calculations, assessments, reviews, variations, collection, and enforcement.

The purpose of the legislation is to ensure that children receive

appropriate financial support from their parents.

Children Act 1989

The Children Act 1989 places the welfare of children at the centre of decision-making concerning

children. While the CMS is not a local authority children's services

department, any decision affecting a child's

financial wellbeing should be viewed in the context of the child's welfare and best interests.

Human Rights Considerations

Relevant rights may include:

• Article 6 – Right to a fair hearing.
• Article 8 – Right to respect for private and family life.
• Article 14 – Protection from discrimination.

Where decisions are based on

inaccurate information, procedural unfairness, or failure to consider

evidence, concerns may arise

regarding fairness and proportionality.

Common CMS Errors

Incorrect Shared Care Records

The CMS may:

• Record fewer overnight stays than actually occur.
• Ignore evidence of shared care.
• Fail to properly consider court orders.
• Fail to consider long-term
• established care arrangements.

Incorrect Income Information

The CMS may:

• Use inaccurate income
• figures.
• Use outdated financial information.
• Misinterpret self-employment records.
• Fail to consider relevant evidence.

Reliance on Unverified Information

Concerns can arise where decisions appear to rely on:

• Hearsay.
• Assumptions.
• Unverified allegations.
• Incomplete information.
• Information contradicted by documentary evidence.

Administrative Errors

Examples include:

• Incorrect arrears calculations.
• Missing payment records.
• Failure to process evidence.
• Failure to record telephone discussions.
• Delays causing financial loss.

If a paying parent has shared care and the CMS uses false information, ignores evidence, or makes an

incorrect decision, the financial

impact on the child can arise in many ways. Examples include:

1. Incorrect Shared Care Calculation

• The child stays with the paying parent 3 nights a week, but CMS records only 1 night.
• The paying parent pays more maintenance than they should.
• The paying parent has less money available to provide food, clothing, activities, school
• supplies, and transport during their periods of care.
• The child's standard of living is reduced while staying with that parent.

2. False Income Information

• CMS calculates maintenance using an income figure that is too high.
• The paying parent struggles to meet both maintenance
• obligations and the costs of caring for the child during shared care.
• The child may miss out on
• outings, educational activities, or other opportunities when with the paying parent.

3. Ignoring Housing Costs

• Excessive maintenance demands may place the paying parent's housing at risk.
• The parent may have to move to smaller or unsuitable accommodation.
• The child may lose access to a suitable bedroom or living
• environment during contact periods.

4. Debt and Enforcement Action

• CMS pursues arrears based on incorrect information.
• Enforcement action causes
• financial hardship.
• Money that would otherwise be spent directly on the child is
• diverted to debt repayments,
• enforcement fees, or legal costs.

5. Travel Costs for Shared Care

• The paying parent incurs
• significant travel costs to
• facilitate contact.
• If CMS fails to properly consider circumstances, the parent may struggle to fund travel arrangements.
• Reduced contact can affect the child's relationship with that parent.

6. School and Educational Expenses

• The paying parent can no longer contribute to school uniforms, books, computers, internet
• access, or extracurricular activities.
• The child's educational opportunities may be affected.

7. Medical and Special Needs Costs

• The paying parent may be
• unable to contribute towards
• therapy, specialist equipment, prescriptions, or disability-
• related expenses.
• The child may experience reduced support.

8. Emotional Impact Through Financial Stress

• Significant financial pressure on the paying parent can create stress and instability.
• The child may witness conflict, anxiety, or difficulties
• maintaining routines.
• Emotional wellbeing can be
• affected even though the issue began as a financial decision.

9. Loss of Contact Opportunities

• Financial strain may make it
• difficult to maintain overnight stays, holidays, or regular activities.
• The child may lose valuable time with the paying parent.

10. Failure to Investigate False Allegations

• If CMS accepts allegations
• affecting shared-care arrangements without proper verification,
• maintenance calculations may be wrong.
• The child may suffer financially because decisions are based on inaccurate information rather than actual care arrangements.

Possible Complaint Wording

"The Child Maintenance Service's

reliance on inaccurate information has not only affected the paying

parent but has also caused financial detriment to the child. The child spends substantial time in the

paying parent's care and relies upon that parent to provide accommodation, food, clothing, transport,

educational support, and emotional stability. By failing to accurately

assess the circumstances and shared-care

arrangements, the CMS has reduced the resources available for the child's direct benefit during periods of shared care, contrary to the purpose of ensuring the child's financial welfare."

How Incorrect Decisions Can Financially Harm Children

Many people assume that child maintenance disputes affect only adults. This is incorrect.

Where there is shared care, the child often relies upon both households for financial support.

Reduced Living Standards

If maintenance is calculated incorrectly:

• Less money may be available for food.
• Less money may be available for clothing.
• Household budgets may become strained.
• The child's standard of living may fall.

Housing Difficulties

Incorrect assessments can result in:

• Financial hardship.
• Rent arrears.
• Mortgage difficulties.
• Loss of suitable accommodation.

Children may lose access to a

suitable bedroom or living

environment during shared care periods.

Educational Impact

Financial pressures may affect:

• School uniforms.
• School trips.
• Computers.
• Internet access.
• Educational resources.
• Extracurricular activities.

Reduced Contact Opportunities

Financial strain may affect:

• Travel arrangements.
• Holiday contact.
• Activities between parent and child.

This can damage important family relationships.

Emotional Impact

Financial instability can contribute to:

• Stress.
• Conflict.
• Anxiety.
• Reduced emotional wellbeing.

Children often experience the

consequences of financial disputes even when they are not directly involved.

Payment Protection and Evidence Protection

Every parent should keep:

• Bank statements.
• CMS letters.
• Emails.
• Text messages.
• School records.
• Medical records.
• Child Benefit information.
• Court orders.
• Parenting schedules.
• Contact logs.

Important evidence may include:

• School attendance records.
• GP registration records.
• Childcare invoices.
• Travel records.
• Witness statements.
• Photographs showing living arrangements.

Never rely solely on verbal

discussions with the CMS.

Always request written confirmation.

Challenging a CMS Decision

Step 1 – Request a Mandatory Reconsideration

If you believe the CMS decision is wrong, request a Mandatory Reconsideration. This is the first formal challenge process. Requests generally need to be made within one month of the decision, and should

explain the errors and include

supporting evidence.

Provide:

• Detailed chronology.
• Documentary evidence.
• Explanation of errors.
• Shared care evidence.
• Financial evidence.

Step 2 – Appeal to the Tribunal

If the Mandatory Reconsideration is unsuccessful, you may appeal to the Social Security and Child Support Tribunal. The tribunal is independent of the CMS and can consider

evidence and legal arguments. Appeals are generally required within one month of the Mandatory Reconsideration notice.

Step 3 – Formal Complaint

Where the issue concerns service failures rather than the calculation

itself, submit a formal complaint to the Department for Work and Pensions complaints process.

Examples include:

• Failure to respond.
• Lost evidence.
• Delays.
• Administrative errors.
• Failure to follow procedures.

Step 4 – Independent Case Examiner

Where complaints remain unresolved, cases may be referred to the Independent Case Examiner after the complaints process has been exhausted. The service investigates maladministration and poor service.

Step 5 – Member of Parliament

You can ask your MP to intervene where there is evidence of serious delay, maladministration, procedural unfairness, or unresolved complaints.

Step 6 – Parliamentary and Health Service Ombudsman

In some circumstances, complaints can ultimately be referred through an MP to the Parliamentary and Health Service Ombudsman after the

appropriate complaints procedures have been completed.

Key Principles

Parents should expect:

• Fair treatment.
• Accurate calculations.
• Evidence-based decision making.
• Proper investigation of disputed facts.
• Recognition of genuine shared care.
• Transparent decision making.
• Protection against
• administrative error.

Conclusion

The child maintenance system exists for the benefit of children. When decisions are based on inaccurate information, unverified allegations,

administrative errors, or a failure to properly recognise shared care

arrangements, children can suffer real financial harm.

Protecting children requires more than collecting maintenance payments. It requires accurate, fair,

evidence-based decisions that

recognise the role both parents play in

supporting their children. Where errors occur, parents should preserve evidence, challenge incorrect

decisions promptly, and use every available review, appeal, and

complaint process to ensure that the child's financial welfare remains protected.

Income Variability and the Use of Averaged Weekly Income in Child Maintenance Assessments

Purpose

This evidence paper examines whether converting annual earnings into a fixed weekly income

accurately reflects the financial

reality of individuals whose earnings fluctuate throughout the year.

The issue is particularly relevant to:

• Self-employed workers

• Agency workers

• Contractors

• Overtime-based employees

• Commission earners

• Seasonal workers

• Individuals with sickness absences

• Workers experiencing reduced hours

Exhibit A – Standard Salary Example

A public salary calculator shows that a person earning £27,000 annually is treated as earning:

£519.23 gross per week

Calculation:

£27,000 ÷ 52 = £519.23

For a salaried employee paid evenly throughout the year this may broadly reflect reality.

The employee receives the same monthly wage regardless of:

• weekends;

• public holidays;

• annual leave.

In such circumstances averaging creates little distortion.

Exhibit B – Income Reality for

Non-Salaried Workers

Many workers do not receive a fixed salary.

Examples include:

Agency Worker

Week 1: £720

Week 2: £340

Week 3: £0

Week 4: £610

Week 5: £280

Annual income may still total:

£27,000

CMS assessment:

£519.23 every week

Actual income:

Varies significantly from week to week.

The assessment therefore reflects an average rather than actual

income availability.

Exhibit C – Construction Contractor

Actual weekly earnings:

January:

£900

£850

£940

£0

February:

£760

£810

£0

£0

March:

£1,050

£1,120

£980

£0

The worker experiences periods with no income.

However, the annual total may still equal:

£27,000

The weekly assessment remains:

£519.23

The calculation therefore assumes income continuity despite evidence of intermittent earnings.

Exhibit D – Seasonal Worker

Worker earns:

April to October only.

Income:

£27,000

Months worked:

7

Months not worked:

5

Actual monthly income while working:

£3,857

Income during off-season:

£0

Assessment:

£519.23 per week for all 52 weeks.

The averaging mechanism ignores periods where no earnings are received.

Exhibit E – Cash Flow Reality

Averaging income creates a

distinction between:

Income Average

Theoretical income over twelve months.

and

Income Availability

Money actually available at a

particular point in time.

Example:

Annual income:

£27,000

Weekly average:

£519.23

Current week earnings:

£170

The average remains £519.23

despite only £170 being available.

The assessment therefore

measures annual earning capacity rather than immediate affordability.

Key Observation

The issue is not that averaging

increases annual income.

Mathematically:

£519.23 × 52 = £27,000

The annual figure remains unchanged.

The concern is that averaging

converts fluctuating earnings into a fixed weekly income stream which may not exist in reality.

Financial Consequences

For workers with variable income this may result in:

• Maintenance demands exceeding current earnings.

• Reliance on credit.

• Rent or mortgage arrears.

• Utility arrears.

• Increased debt.

• Reduced ability to support children during shared care periods.

• Colect and Pay / Direct of Ernings Order (AEO) (DEO)

Economic Reality Test

Question:

Does a person earning £27,000

annually necessarily have £519.23 available every week?

Answer:

No.

The figure represents an average.

It does not prove:

• weekly availability;

• weekly affordability;

• cash flow position;

• current income level.

Evidence-Based Conclusion

The annual-to-weekly conversion method accurately converts annual income into an average weekly figure.

However, for workers whose earnings fluctuate, the calculation

measures theoretical annual earning

capacity rather than actual weekly

income availability.

As a result, the assessment may not accurately reflect the financial reality faced by individuals whose earnings vary significantly throughout the year.

The greater the fluctuation in earnings, the greater the difference between the averaged income used for assessment and the income

actually available at any given time.

Public Law Principles

Even where legislation exists, all

public bodies remain subject to:

Wednesbury Reasonableness

A public authority cannot make a

decision so unreasonable that no reasonable decision-maker could have reached it.

The legal test is extremely high.

• A challenge could arise where:
• CMS knows income has collapsed.
• CMS possesses evidence 
• proving income has collapsed.
• CMS refuses to consider the evidence.
• CMS continues enforcement based on income known to be inaccurate.

At that point the issue becomes:

Was the decision irrational?

Exhibit – Wednesbury Reasonableness and

Decision-Making

Public authorities must exercise their powers reasonably and take relevant information into account when

making decisions.

Under the principle established in Associated Provincial Picture Houses Ltd v Wednesbury Corporation [1948], a public authority may act unlawfully where it reaches a decision that no reasonable

decision-maker could have reached in the circumstances.

The issue is not whether CMS is

permitted to use historical income data as a starting point.

The issue arises where:

CMS is informed that income has significantly reduced.

CMS is provided with evidence of that reduction.

CMS accepts receipt of the evidence.

CMS delays reviewing the evidence.

CMS continues collection or

enforcement action based on

income known to be outdated or inaccurate.

In such circumstances, the question becomes:

"Is it reasonable to continue relying on an historic income figure when more accurate and current evidence is available?"

The longer the delay between

notification and correction, the stronger the argument that the

assessment no longer reflects

reality and may become unreasonable.

Exhibit – Proportionality and Human Rights

The Human Rights Act 1998 requires public authorities to act compatibly with Convention rights.

Article 1 of Protocol 1 protects the peaceful enjoyment of possessions, including earned income.

Article 8 protects family life.

While child maintenance serves a

legitimate public purpose, any

interference with income must

remain proportionate.

Questions arise where:

Assessments are based on income no longer being earned.

Delays prevent timely correction.

Enforcement continues despite

evidence of hardship.

Shared care arrangements are placed at risk due to financial pressure.

The issue is not whether

maintenance should be paid.

The issue is whether the method of assessment and enforcement

remains proportionate when current financial circumstances differ

substantially from historic assumptions.

Exhibit – Shared Care, Child Welfare and Unintended Consequences

Child maintenance policy is intended to support children.

However, where assessments fail to reflect actual income availability, there may be unintended consequences.

Financial pressure on a paying

parent can affect:

Housing stability.

Ability to provide food and clothing during contact periods.

Ability to travel for contact.

Ability to maintain suitable

accommodation for overnight stays.

In shared care arrangements,

children benefit from meaningful

involvement by both parents.

Where affordability issues reduce a parent's ability to maintain shared care arrangements, the child may

experience a reduction in practical support and parental involvement.

It is therefore necessary to consider whether delayed reassessments and reliance on historic income data may, in some circumstances,

undermine the wider welfare

interests of the child.

Exhibit  – Administrative Delay and Public Administration

The effectiveness of any

assessment system depends upon timely correction of inaccurate information.

Where substantial delays occur between:

Notification of changed circumstances;

Submission of evidence;

Review of calculations;

Resolution of disputes;

there is a risk that decisions

continue to be based on information that no longer reflects reality.

Consequences may include:

Accumulation of arrears.

Increased enforcement activity.

Increased complaints.

Additional administrative costs.

Financial hardship for families.

This raises questions regarding

efficiency, value for money, and the effectiveness of public administration.

The issue is not solely individual hardship but whether systemic delay creates avoidable costs and

unintended outcomes across the wider CMS system.

How These Arguments Can Be Used in Individual CMS Cases

1. Wednesbury Reasonableness

When it applies

A parent has informed CMS that their circumstances have changed significantly.

Examples:

• Redundancy
• Long-term sickness
• Business collapse
• Reduced hours
• Retirement
• Significant drop in earnings

The parent supplies evidence.

CMS continues to use old figures despite having evidence that those figures no longer reflect reality.

Argument

"I am not challenging the legislation.

I am challenging the reasonableness of continuing to rely upon income

information that CMS knows is inaccurate.

The decision is based upon outdated information despite the availability of more accurate evidence."

Evidence Needed

• Payslips
• Bank statements
• P45
• Employer letters
• Universal Credit statements
• Self-employed accounts

2. Procedural Fairness

When it applies

CMS:

• ignores evidence;
• fails to explain calculations;
• fails to answer questions;
• fails to investigate concerns.

Argument

"I provided evidence on [date].

CMS failed to explain why that

evidence was rejected or disregarded.

I have therefore been denied a fair opportunity to challenge the assessment."

Evidence Needed

• Emails
• CMS letters
• Telephone logs
• Mandatory reconsideration requests

3. Administrative Delay

When it applies

CMS takes months to:

• review income changes;
• investigate;
• process reconsiderations;
• correct errors.

Argument

"Even if CMS was entitled to review the evidence, excessive delay caused avoidable hardship.

The assessment remained

inaccurate long after CMS was aware of the issue."

Evidence Needed

Create a timeline:

Date income changed

Date CMS informed

Date evidence supplied

Date response received

Date correction made

Total delay period

4. Proportionality

When it applies

Maintenance demands become

disconnected from actual financial circumstances.

Examples:

• Income reduced by 50%.
• Maintenance remains unchanged.
• Parent cannot meet essential living costs.

Argument

"The amount demanded may have been proportionate when the

assessment was made.

It is no longer proportionate given current circumstances and available evidence."

Evidence Needed

Income and expenditure schedule.

Housing costs.

Utility costs.

Travel costs for contact with children.

Debt created by assessment.

5. Shared Care Impact

When it applies

Financial pressure affects the ability to maintain contact arrangements.

Examples:

• Unable to afford fuel.
• Unable to maintain suitable accommodation.
• Unable to fund overnight care.

Argument

"The assessment is having a direct impact on my ability to care for the child during contact periods.

This is contrary to the wider welfare interests of the child."

Evidence Needed

Court orders.

Parenting plans.

Contact schedules.

Travel receipts.

Evidence of overnight care.

6. Human Rights Arguments

When it applies

Usually only after all normal

complaint and appeal routes have been exhausted.

Argument

Article 8 (Family Life)

"The financial impact of the decision affects my ability to maintain

meaningful family life with my child."

Article 1 Protocol 1 (Property)

"The assessment interferes with my income based upon information that no longer reflects reality."

These arguments are usually

supporting arguments rather than primary arguments.

7. Affordability Argument

When it applies

A parent can demonstrate:

• Income reduction.
• Essential expenditure.
• Financial hardship.

Argument

"The issue is not unwillingness to support my child.

The issue is affordability and the need for an assessment based on current circumstances."

Evidence Needed

Income and expenditure breakdown.

Bank statements.

Rent or mortgage statements.

Council tax.

Utility bills.

Evidence of other dependent children.

Strongest Individual Case Strategy

The strongest cases usually follow this structure:

1. Income changed.
2. CMS was informed.
3. Evidence was supplied.
4. CMS delayed or ignored evidence.
5. Assessment remained inaccurate.
6. Hardship resulted.
7. Shared care or child welfare was affected.

That becomes a factual challenge to the way CMS handled the case rather than a challenge to the

legislation itself.

Those arguments are much harder for CMS, ICE, MPs, Ombudsman

investigations, or courts to dismiss.