A simple change means workers could "double or triple" their pension money, claims a financial expert.
Money Saving Expert founder Martin Lewis urged people to look at their retirement savings pot now.
In an episode of his ITV show, he delivered some key advice which could boost pension funds for retirement.
He explained how private workplace pension schemes work and advised everyone to change their policy immediately for easy gains.
For every amount put by for later life, he said you pay less tax on what's saved into the pension and your workplace will match that.
It means that if you're a basic rate taxpayer and you put £100 in, you get another £60 from your employer, Lancs Live reports.
Normally you would only keep £80 out of every £100 you earn because £20 would be taxed.
For a higher rate taxpayer, you only keep £60 out of every £100 over the higher rate threshold.
But because the money is matched by the employer and it isn't subject to income tax, you stand to almost double or triple your money by making sure you're enrolled in the workplace scheme.
Martin explained: "In effect, you lose £80 in your pay packet but you get double that - £160 - going into your pension.
"For a higher rate taxpayer it costs you £60 and you get £160, nearly treble going into your pension.
"This is unbeatable - there's nowt out there like it which is why my big message is, opt out and you're effectively giving up a payrise and you're giving up the tax benefits too.
"Of course you're going to take home less but what you get in the pension return is so good, so don't opt out unless you absolutely have to.
"For those people who have not automatically been opted in, many can and some of you should choose to, because your employer must let you join and it must contribute if you're aged between 16 and 74 and you earn over £6,742.
"Let's imagine there's a 21-year-old living at home with no expenses it's a dream time to start your pension.
"Just cos you're not opted in just ask to join."
Martin then explained the amount of your income you should put in your pension.
He said you should take the age you started your pension, divide it by two and then put that percentage in for the rest of your life.
So if you started at 22 you should put 11% of your earnings in.
"Nobody gets close to that but the big thing about that equation it shows the earlier you start the better. 8% isn't quite up to the equation but put in what you can, max this out."
