People working in certain positions can influence how they are paid and the amount of pay they get, such as those who are self-employed, have a side hustle or working as sole traders. The Child Maintenance Service (CMS) refers to them as “complex earners”, because it gives them an opportunity to reduce the amount of child maintenance they pay. But what can you do if your ex is lying about being unemployed? Is there anything that can be done about an ex suspected of not declaring their true income? We find out.
People working in certain positions can influence how they are paid and the amount of pay they get, such as those who are self-employed, have a side hustle or working as sole traders. The Child Maintenance Service (CMS) refers to them as “complex earners”, because it gives them an opportunity to reduce the amount of child maintenance they pay. But what can you do if your ex is lying about being unemployed? Is there anything that can be done about an ex suspected of not declaring their true income? We find out.
How is child maintenance calculated?
In order to understand whether you can take further action when an ex is lying about their income, you must first understand the rate at which they should pay child maintenance where all income is properly declared.
When calculating child maintenance, the CMS doesn’t take the number of hours worked into account and instead uses the paying parent’s gross weekly income to determine the sum payable. This makes it difficult for a receiving parent to understand when a child support liability kicks in or if the figure has been incorrectly calculated because of the lie.
Essentially, child maintenance is payable if the paying parent falls into any of the following gross weekly income brackets (figures correct at the time of writing):
- Basic rate: between £200 and £800
- Basic plus: £800.01 – £3,000 (the first £800 is taken into account using the basic rate)
- Reduced: £100.01 – £199.99
- Flat: £7 to £100 (or receives benefits)
- Nil: less than £7 (no child maintenance is payable)
What if my ex isn’t declaring their true income?
Whether your ex is claiming to be unemployed, working cash in hand, self-employed or living off money from a relative, if they fail to declare their true income, the receiving parent can apply to the CMS for an “additional income variation”. You can apply for a variation in the following circumstances:
- Unearned income – for example, rental income the paying parent receives from property or land, dividends, or interests from savings and investments. This type of income must be at least £2,500 per year (correct at the time of writing)
- Notional income from assets – this is income that the CMS works out the paying parent could receive based on certain types of assets they own, providing the total value is £31,250 or more (correct at the time of writing)
- Earned income – this is when the paying parent is in receipt of benefits and qualifies to pay Flat rate child maintenance, but also has income from a pension, employment or self-employment. This type of income must be at least £100 per week (correct at the time of writing)
- Diversion of income – the CMS will consider a variation if it believes the paying parent is controlling, whether this is directly or indirectly, the amount of income they get by diverting it to another person or purpose, which means it isn’t included in the figure used by the CMS to calculate child maintenance.
You can apply for a variation at any time during the life of a child maintenance case. It will take circumstances into account which are not part of the standard way child maintenance is worked out.
How does the CMS investigate more complex cases?
If a paying parent is suspected of concealing their true income, the Financial Investigations Unit (FIU) can investigate. The FIU works with HMRC records and other information to assess and uncover additional income. If relevant, it also passes information onto the HMRC which may have tax implications.
Additional income and evidence collected by the FIU may be used by the CMS to calculate child maintenance assessments. The CMS can order the paying parent to pay the child maintenance they’ve previously avoided. Although it should be noted, the CMS does not have the power to investigate paying parents who live outside the UK.
The CMS can forward cases to the FIU if they believe there to be “credible, evidence-based challenges to a child maintenance assessment” that cannot be resolved through standard processes. The FIU does not, however, accept referrals on cases where the receiving parent challenges the income without providing them with any supporting information.

What evidence must I have to prove my ex is lying about their work status?
The receiving parent does not necessarily have to provide evidence, but they do need to have credible information to support their position. The CMS/FIU should not ask the receiving parent to source information they do not, or should not have, as this may put them into a compromising situation.
Credible information includes, but is not limited to:
- Knowing the paying parent keeps two sets of books
- They “fiddled” their books when you were together
- Significant information showing their lifestyle doesn’t match the income declared
What can the CMS do if they find in my favour?
If the CMS/FIU finds in your favour, and your ex refuses to pay, they can apply to the court for a liability order. This allows them to try to recover the outstanding monies in other ways. Once a liability order has been made, the CMS doesn’t have to use it straightaway. They may wait to see if the paying parent can keep to an arrangement they’ve made. But if they choose to use the liability order, they have to act within certain time limits, depending on which enforcement method they use.
Once a liability order has been granted, the CMS can take further action, such as:
- Using sheriff officers for an attachment and exceptional attachment, which may involve the officers going to the paying parent’s home to value their belongings that could then be sold to pay off the arrears
- If the paying parent owns a property, the CMS can apply to court for an inhibition order. This controls what they can and can’t do with the property, and will, for example, prevent them from selling it while the inhibition order is in place
- Arrest funds in the paying parent’s bank account(s)
If these methods are unsuccessful, the CMS can apply to the court to:
- Disqualify the paying parent from driving
- Send the paying parent to prison
If the CMS applies for a liability order, the paying parent will also be liable to pay court fees as well as an administration fee to the CMS, which has the effect of increasing the amount owed.
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