After the government said it would close a legal loophole that allowed "a small minority" to avoid making child maintenance payments, we asked for your experiences.
The loophole identified by the Department for Work and Pensions (DWP) relates to a rule that says money can be taken only from bank accounts held solely by those responsible for paying - allowing people with joint accounts to avoid paying.
While the law change has been welcomed, many readers have got in touch about other ways the system is being exploited.
Creating complex financial arrangements that are hard to keep track of due to self-employment
Putting a businesses in another name to distort personal wealth
Opening a limited company to make money unavailable
Reopening a case with the CMS after a legal agreement was already reached in court
Julie, from Northern Ireland, said her problems arose from her ex-husband's self-employment status.
She said the CMS is unable to keep up with complicated financial arrangements or people who move their money around.
"The CMS is set up for people who are honest and open about their affairs," she said.
"There are so many loopholes [and] the CMS doesn't have the power to enforce anything when it comes to those who are self-employed.
"I had a deduction of earnings order but they can't stop money being moved around in different accounts, cash being taken out and hidden.
"If someone who is self-employed says they need cash for the business or to pay wages, that takes precedence."
Julie added that if there were arrears and one or two small payments were made, the CMS moved on.
"They can make one or two small payments and then you're back at square one and you have to go through the whole process again.
"It gives the ex-partner power and control over the family and I hate it. It is the children that suffer in the end."
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Parents use the government-run Child Maintenance Service (CMS) if they are unable to come to a family-based arrangement.
Fiona, who lives in Scotland, had been receiving regular maintenance for 12 years from her ex-husband based on a court agreement, but that changed last year.
After becoming unemployed, her ex-husband went to the CMS and asked for his case to be reopened and she hasn't received anything since.
"I previously had a court-based agreement with my ex-husband and he never defaulted once."
She said there was no need to reopen the case as the original agreement made provision for "a drastic change in circumstances".
"But now it is with the CMS I can no longer take him to court for unpaid maintenance. I think this is a much bigger loophole," she added.
She has not been told why he "was allowed to open a case when we had a legally binding agreement in place".
Dalia Ben-Galim, policy director at Gingerbread - a charity helping single parents - recognised these additional loopholes.
"What we find is often around the relationship between those who do self-assessment tax - for example, self-employed, those who have income from other sources - rental income or as a result of dividends or as a company director," she said.
"It's very hard at the moment for the DWP, for the child maintenance service, to connect with HMRC to understand that additional income."
Samantha, from Gloucestershire, has three children with her ex-husband, who has now remarried.
She says he has put his businesses, house and bank accounts into his new wife's and brother's names, to avoid paying child maintenance.
"It's an absolute joke and I feel that the Child Support Agency (CSA) are completely useless. He made the children, he should pay to support them," she said.
The government is in the process of moving CSA cases to the new CMS.
The CMS assess parents on a range of measures to calculate payments
A parent from Southampton, who wished to remain anonymous, said: "My ex-partner has not paid a penny for over three years. He opened a limited company solely to avoid paying his maintenance.
"A liability order was granted in February 2017 for payments up to September 2016 but they are only just taking bailiff action now.
"They never call back when they say they are going to. It's constant chasing on my part. My children are now owed well over £5,000.
"There are too many loopholes."
The DWP has said only a small minority of parents try to cheat their way out of paying towards their children.
But Gingerbread would like to see the government do more to close other loopholes.
It wants the DWP and CMS to "routinely count all income held by HMRC - especially in making the CMS aware of other income, for example from those who are self-employed or have rental income".
I fully agree that using self employed / Limited company status to avoid paying an acceptable level of Child Maintenance should be condemned. It is not a black and white situation however.
I moved from PAYE to Limited(not through choice) and what became clear was that essentially I moved from being assessed on gross to net income. This caused a large reduction in the CM I was expected to pay. This was not caused by me gaming it, but through the CMS processes itself.
I tried to increase my payments by offering more for my ex to go voluntary and in line with previous PAYE. She refused because she was and remains convinced I am sitting on a pot of gold and doing all sorts of tricks to avoid paying her what she is due.
The result is for the last 2 years she has been receiving 300 per month, when I offered 600. Her response has been to continue trying to get CMS to investigate me, through tribunals, reconsiderations etc, rather than cancel CMS involvement and take the 600.
I believe in many cases the Resident Parent could negotiate a much better deal with the NRP by doing just that - discuss amicably and negotiate. But some prefer the aggressive approach and concentrate more on their angst at the ex husbands not paying exactly what they may be due to pay, rather than what they need or is fair.
My ex gets paid 50K a year, has a nice fat pension coming and gets child benefit. I offered 600, which is a big outgoing for me and for one child I believe covers most if not all direct and associated costs. However, what she has done is refused to discuss, continue taking the lower amount and use it to tell everyone she knows that I am refusing my responsibilities due to being self employed.
Aware that not all situations are the same, before I get crucified :-)
lol good on her, let her wait on phone for half an hour with CMS
in ideal world, would be better to have private arrangements with ex's. but we have read on here, how so many of them are just a pain in the back side. in private arrangements they just keep demanding more and more money and then try deprive the dad of seeing the kids because of it.
for me, i dont even have direct contact with ex. instead i got her greedy family members trying to get as much out of me as possible, like they did during wedding arrangements. so i told them to sod off and I am paying £20 to register with CMS. so now i am much better off and no more money fights
i've been self-employed for few years before marriage broke. i think i would get crucified if i was in perm job. CMS should consider if ex is working, assess that and give the paying parent deductions. that would be good justice.
mine was 15 years ago, so before a lot of the changes. My ex was trying to avoid paying maintenance, so she paid 100% of income into a pension. I took her to a tribunal and they decided that they would discount the whole payment to pension (I was expecting them to allow some of it) and she was liable for maintenance on the whole of her salary.
So while the rules worked for most, the tribunals were there to deal with exceptional cases, and it seemed to work well - that seems to be the bit that's missing, a way to deal with the small number of cases that the rules don't sensibly allow for.