Halifax is making belated payments to thousands of its Clarity credit card customers after failing for years to pay monthly rewards to those who'd earned them, MoneySavingExpert.com can reveal.

Some cardholders have received lump sum payments of more than £100 as a result, but Halifax has admitted it's still trying to track down some former customers who are owed money but no longer have a Halifax Clarity card.

The Halifax Clarity credit card is a longstanding top pick in our Travel Credit Cards guide. Until last year, cardholders who also had a Halifax current account could earn £5/month cashback for every month they spent £300 on the card.

However it's now emerged some cardholders weren't actually receiving these rewards, with some missing payments dating back to 2011. Halifax is now in the process of contacting affected customers to explain the situation and is paying those customers the amounts they're owed, plus interest.

The bank has told us that about 1.5% of all Clarity cardholders are affected – MSE understands the total number owed money is in the low thousands.

For more info on what rewards you can earn for spending on your credit card, see our Credit Card Rewards guide.

'I've discovered two credits totalling just over £100'

The exact amount cardholders are owed depends on when they had a Clarity card and Halifax current account and how many monthly rewards they missed out on, but in some cases MoneySavers have told us they've received sizable payments.

News of Halifax's blunder first emerged after reports in the MSE Forum of unexplained credits on Clarity cardholders' accounts.

Forumite WhoKnowsKT89 said: "I just logged in to my online banking to find on my credit card two credits from Halifax, one stating 'missing reward' and one 'additional interest'. This totals just over £100."

Fellow forumite LonelyOutPost added: "I've discovered the same two credits on my card this morning as well, totalling just over £100. I'm guessing this is some reward that we are entitled to but which they never paid."

How to check if you're owed

Halifax has assured us it is getting in touch with ALL affected cardholders and any payments owed will be added as a credit to their accounts. But if you think you may have missed out on Clarity rewards in the past then check your old credit card statements, and get in touch with the bank if necessary.

If you're a former Clarity cardholder, you should in due course receive a letter from Halifax in which you'll be asked to provide info on how you would like to receive your missing rewards payout.

But a Halifax spokesperson told us it may take longer for it to track down ex-customers whose contact details are no longer up to date. If you think you're owed, again, contact the bank.

It's worth bearing in mind that Halifax no longer offers this £5/month reward. It was stopped for long-standing customers on 30 September 2016, while those who got a Halifax Clarity card up until 9 August 2016 were paid them until the end of last year.

What does Halifax say?

A Halifax spokesperson said: "We have identified that some of our Clarity card customers did not receive the £5 reward earned on their account when qualifying criteria were met.

"We are now in the process of paying these customers the amounts they are owed along with the interest they are due and apologise for any inconvenience this may have caused."