Martin Lewis: Are you missing out on these possible cash windfalls?

Green light for supercar brand in Leeds as McLaren steps business up a gear1. Over 1 million are owed a refund on Power of Attorney registration fees

A Lasting Power of Attorney is a legal document which allows you, while you still have the mental capacity to do so, to nominate a trusted friend or relative to look after your affairs if you lose capacity. And they’re not just for the elderly, I have one, I’m 45. For more on how to do it cheaply go to http://mse.me/poa.

Yet if you’ve already got one, and did it between April 1, 2013 and March 31, 2017 in England and Wales, you paid £110, which is more than it should’ve been, so if you did that you’re owed up to £54 per Power of Attorney (which includes 0.5% interest).

To claim a refund go to www.gov.uk/power-of-attorney-refund or call the Office of the Public Guardian’s on 0300 456 0300 and select option six. You’ll need details (including bank details) of the person who it was set up for and the name of one of the attorneys.

I’m swamped with people telling me how easy it is, like Barbara who tweeted me: “@MartinSLewis Thanks to you, I have £75.42 back. How else would I have known about this?”

2. Are you married? If so, you may be due a free £900

Three years ago, the Government launched the marriage (and civil partnerships) tax allowance. It applies where one is a basic-rate taxpayer and the other a non-taxpayer.

The non-taxpayer can apply to have 10% (£1,190) of their tax-free allowance shifted to the taxpayer. This means £1,190 of income they were taxed on at 20% is now tax-free – a £238 gain this year done via altering your tax code.

Yet still over 1 million eligible couples are missing out. And you can back claim a refund to when it started too, so that’s a cheque for £662 – making a total of £900. It takes five minutes to do at www.gov.uk/marriage-allowance/how-to-apply – it’s the non-taxpayer who must apply.

As Michelle who tweeted: “@MartinSLewis just applied for the marriage tax allowance and it took 2 mins to get over £600. #thankyou.”

3. Reclaim overpaid energy

With winter long gone this is the perfect time for those who pay energy by monthly direct debit, which is the vast majority, to check if you’ve got too much credit. This is because energy firms estimate your usage, and then bill you based on their estimates.

If those are set too high you can end up overpaying.

Only do this if you’ve been providing regular meter readings, or have a smart meter doing it for you. If not, send them a meter reading. Assuming all is up to date go online or call up to check whether you are in credit and if so how much.

Direct debits are meant to smooth out your usage over the year so normally you’re in surplus going into winter and in deficit after. So right now if your credit is more than a month’s worth of bills, ask them for the amount over that back – it can be £100s, and ask them to lower the direct debit going forward.

If you’ve switched providers you should’ve been credited with any excess then, yet they didn’t used to, so check now even if it was years ago”

Leeds soldier Simon Brown: ‘I lost my sight to a sniper in Iraq... but I was one of the lucky ones’4. Graduated uni? You may be due £100s back

In the last three years alone, over 100,000 university leavers started to repay their loans too early, and are due some of it back. Plus as this could go all the way back to 1998 it’s likely there are 100,000s more.

You are only eligible to start repaying your student loan in the April after graduation – often around nine months after leaving, and even then only if you earn over a set threshold

However, if your employer has the wrong info about your uni leaving date, or simply does it wrong you may start repaying early.

To check and get it back is easy. Just call the Student Loan Company on 0300 100 0611 and ask it.

It takes five minutes and I’ve had tonnes of successes.

And that’s only one category of student loan over-payment, there are other reasons to, to check see my full www.mse.me/studentloanoverpayments guide.

Tom Richmond: How Chris Grayling misled the North over rail electrification – and why he should now resign5. Get a tax rebate if you wear a uniform

If you wear a recognisable uniform to work, even if it’s just a branded t-shirt, and you wash it yourself, you may be able to reclaim hundreds of pounds of tax back.

And you don’t need to pay anyone to do this, just fill out the P87 claim form at www.gov.uk/guidance/claim-income-tax-relief-for-your-employment-expenses-p87.

Once you’ve registered, your tax code will change, so you’ll be taxed less in the future. Full help at www.mse.me/uniform.