I was a guest on Nicky Campbell's phone in show on Radio Five Live this week answering points about debt and general hard-upness. But I was not prepared for the call from - I'll call her Jayne - who was a single parent with a 17-year-old son. When he left college she stopped getting child benefit and child tax credit for him and her income fell from £138 a week to just £67.50 a week. That's the income support she gets to keep herself. Her arthritis prevents her from holding down a job but is not bad enough to get more help as a disabled person. So Jayne is now keeping two people - one of them a 17 year old boy - on the money intended for one.

I spent an hour or two after the programme investigating this rather surprising state of affairs and I found it is correct. No child benefit or child tax credit is paid to the parent of a 16 or 17 year old who is not in education or training. And the young person cannot normally get jobseeker's allowance even if they are seeking a job.

But there are a couple of things Jayne and her son may be able to do to get a bit more money for a limited period. No-one at HMRC - which administers child benefit and child tax credit - had mentioned this to her. And no-one at the Job Centre had suggested either of them to her son.

First, Jayne could get her child benefit extended for up to 20 weeks. Second, her son might be able to get jobseeker's allowance due to 'severe hardship'. There is no guarantee that he would and if he did it would only last for eight weeks before he had to ask again. They are now going to see if they can get this help from either of these sources - one at a time as they can't get both.

Meanwhile, Jayne and her 17-year-old son, who "eats a lot" Jayne told me, are living on the £67.50 intended to keep one adult.

***IN MONEY BOX THIS WEEK***

Would you like to join with tens of thousands of other householders to negotiate a cheaper deal for your fuel? We talk to the Dutch consumer union who has saved more than 100,000 people an average of around €300 each in just this way. And to Which? who are launching a similar plan here.

We try out the Barclays scheme for sending money to a mobile phone knowing no more than the mobile number. And look at other financial apps for your smartphone.

As inflation falls and new savings deals come on the market we ask where can you beat inflation with your savings or ISA?

If a Coding Notice from HMRC arrived in your post recently have you checked it? Failing to do so could mean you pay the wrong tax all year. We explain what the numbers and letters mean and what to look out for.

And we will try to squeeze in 'thin files' - the technical term for a credit record with almost nothing on it which can stop you getting credit as much as a fat file with missed payments.

Find out if we manage to get all that in by listening on Saturday at midday, or Sunday at 9pm, or anytime online. Remember you can put in a regular order for our podcast. It's free.

General insurance is the topic on Money Box Live with Vincent Duggleby (it's my month off) on Wednesday at 3pm. Call with your question after 1pm on Wednesday 22nd February on 03700 100 444 or email through the website when the programme page is up later today. Or of course just listen.

Best wishes,

Paul

PS. I will be on Breakfast on BBC One around 0845 on Saturday with a programme trail and back on Breakfast later in the week, probably on Thursday and usually around 0640 and 0820 talking about a money story and answering emails and tweets. But the time, and occasionally the day, can vary.