Martin Lewis' website Money Saving Expert has warned people to make sure their bank has their correct contact details or they risk having payments declined.
The issue was raised in Martin's latest Money Saving Expert newsletter, with debit and credit card firms rolling out the measure as soon as this month.
The new verification processes are being rolled out by the firms in a bid to combat fraud.
It's likely that online payments over £25 are more likely to be checked under the new system.
Firms often use your phone number to verify it's you and if it's wrong your payment could be declined.
You should also ensure that your card provider has your landline number and email address if you have them.
Money Saving Expert said: "The changes are coming in under new fraud-prevention rules, known as 'Strong Customer Authentication (SCA)', which require both debit and credit card providers to ask customers to verify certain payments.
"As a result, you may get a text or phone call from your card firm when you make an online transaction, requiring you to confirm you are who you say you are - so don't just ignore this or wrongly assume it's a scam.
"Card firms aren't required to have the new checks in place until 14 March 2022 - a deadline that was recently pushed back from 14 September 2021 due to the pandemic.
"But the Financial Conduct Authority (FCA) last week began encouraging firms to implement these measures and several card firms have told MoneySavingExpert.com they're beginning to gradually roll out new verification processes this month."
