If you're one of the roughly one million people - mostly women - about to receive a letter from HMRC about a pension top-up, rest assured: it's not a scam. It just looks, smells, and is delivered exactly like the kind of thing your bank warned you about.

The letters, which will go out over the next few months, explain how low earners who missed out on pension tax relief due to their employer's use of a Net Pay Arrangement scheme can receive a top-up. Typically, the payment is around £70, though it can vary considerably depending on circumstances. Because nothing says 'government efficiency' like a letter that might contain wildly different amounts.

The issue arises because when you pay into a pension, the government allows some money that would have gone to tax to go into your pension instead - a concept known as tax relief. But for reasons too complicated to explain without a flowchart and possibly a stiff drink, some low earners using Net Pay Arrangement schemes got less than those using Relief at Source schemes. Employees have no control over which scheme their employer uses, so the government has decided to make it right with what's called a 'low earner's pension payment.'

Eligible individuals typically earned close to, but not more than, £12,570 a year - the income tax starting point. The top-up payments will initially cover the 2024-25 tax year, with automated payments for subsequent years following. You don't need to apply; if eligible, you'll be contacted by HMRC via letter or your online personal tax account.

Here's where the scam-awareness part kicks in: HMRC will not text, email, or call you about this. If someone does, it's a scam. They will also never ask you to transfer money or provide PIN codes or passwords. To verify a letter is genuine, you can search Gov.uk for 'Low Earner's Pension Payment' or check HMRC's scam advice. Customers will be asked to provide bank details through their personal tax account; those who are digitally excluded can phone HMRC.

"We know some people may be cautious about unexpected contact, which is why we provide clear information about what to expect and how to verify the contact is genuine," said an HMRC spokesman, in a statement that sounds reassuringly like something a real organization would say.

But Sir Steve Webb, partner at pensions consultancy LCP and a former pensions minister, is worried. He's shocked at how few people the government expects to actually take up the payment. The government has estimated the cost of the project to be much lower than if everyone eligible claimed it - which, let's face it, is probably because they know a good chunk of people will either ignore the letter or assume it's a scam.

"The process of getting these payments to the right people is going to be incredibly painful and there is a real risk of huge non take-up," Webb said. "It is vital that communications are effective to make sure that people get the money to which they are entitled."

HMRC says it will run an awareness campaign using social media and other channels. So keep an eye out for ads that look suspiciously legitimate. And remember: if it's a letter, it might be real. If it's a text, it's probably not. You're welcome.

In related news, you could be missing out on £150 off your energy bill - but that's a different letter, and we're not getting into that now.