Martin Lewis is advising pensioners to check if they are eligible for a state pension boost which could "transform their finances".
The money saving guru told listeners on his podcast that they have the chance to take the "biggest single action" by paying a maximum of £820 to gain £6,000.
Taxpayers now have until April, 5 2025 to fill gaps in their National Insurance record from April 2006 which could increase their payout.
The previous deadline of 31 July had received backlash as people were unable to get through to the advice line to find out if they were eligible.
Lewis said one person who followed his advice gained £83,000 in state pension payments for his wife.
Taking on Twitter to promote the podcast he said: "V important listen! Millions may be able to pay max £820 to gain £6,000! It's all about boosting ur state pension & the deadline's just changed."
He said: "For many people today this is the biggest single action you can take that transforms your finances. There are millions of people who are not due to get the state pension.
"Buying voluntary contributions is a way for you to get the full state pension - not that everyone has to buy them. Some people are eligible for free national insurance years they don't know about.
"The extension means there's more time to do this so there's more time to save.
"But just to give you an example, someone got in touch with me over the last couple of weeks, who, having heard me talk about how to do it is going to gain for his wife £83,000. That is the scale of change of what we're talking about today.
"This is crucially important if you're aged between 45 and 70 if you're a woman and up to 72 if you're a man."
Extending the voluntary National Insurance contributions deadline means people have more time to properly consider whether paying the contributions is right for them and ensures nobody misses out on the possibility of boosting their entitlements.
Victoria Atkins, Financial Secretary to the Treasury, said: "People who have worked hard all their lives deserve to receive their State Pension entitlement, and filling gaps in National Insurance records can make a real difference.
"With the deadline extended, there is no immediate rush for people to complete gaps in their record and they will have more time to spread the cost."
Before beginning the process, eligible individuals with gaps in their National Insurance record from April 2006 onwards should check whether they would benefit from filling those gaps.
They can find out how to check their National Insurance record, obtain a State Pension forecast, decide if making a voluntary National Insurance contribution is worthwhile for them and their pension, and how to make a payment on GOV.UK.