Over the past year, more than a million employees of large firms have been covered by the new regime; from October 1 it will reach firms with 800 employees; and from November, 500, so many more workers will start to see new deductions on their payslips.
However, it will be 2017 before all employees find themselves obliged to be enrolled in a company-sponsored scheme, unless they opt out within a month.
But whenever they are enrolled, anyone who assumes their pension provision requires no further thought risks a nasty shock when they give up work.
Laith Khalaf, head of corporate research at brokers Hargreaves Lansdown, said: "Automatic enrolment is a necessary and positive step, but it is not a silver bullet. It risks creating a nation of pension zombies who don't know what they are saving, or why. Unless auto-enrolled workers get help to answer these questions, they will always be in danger of falling off the savings wagon."
Mr Khalaf says what is needed now is "good communications and education in the workforce explaining why workers need to save into a pension and how much they need to save".
Auto-enrolment is designed to ensure most workers have more than the state pension to live on in retirement. Eventually, all employees between 22 years old and state pension age who are not already in a company scheme and earn at least £8105 a year will have contributions deducted directly from their wages.
These will be invested and, from the age of 55, or when they retire, they will be able to buy a pension with their accumulated sum.
The self-employed are still expected to make their own arrangements though, through personal pension plans and other forms of saving.
Anyone can choose to opt out, but those who do will suffer financially in old age unless they make alternative arrangements.
The simplified, single tier state pension, due to come into effect in 2016, will be worth just £144 a week, or £7488 a year - nowhere near enough to fund a comfortable retirement - and many people will be in their late sixties before they are eligible.
Pension plans - workplace or personal - are cost-effective because savers get tax relief on contributions at their highest rate, and the funds are invested in a tax-efficient environment. Workplace schemes usually have the added advantage that the employer makes additional contributions on members' behalf.
Auto-enrolled employees will begin by paying 0.8% of earnings between £5564 and £42,475, with tax relief adding 0.2% and their employer a further 1%.
This means someone earning £25,000 will pay just under £13 a month, or £155 a year, increased by tax relief and employer's contribution to £389.
This will eventually rise to 4% from the employee, 1% in tax relief and 3% from the employer, giving a contribution of 8%. For someone on £25,000 a year, this will give a total investment of just under £130 a month, or £1555 a year.
According to Scottish Widows, the average employee earning £10,000 to £30,000 would like a pension of just under £23,000.
However, assuming typical current company and private pension savings of £250 a month including employer contributions, they will actually end up with just £11,700 including their state pension - or only half their target income.
David Scott, an independent financial adviser with Alan Steel Asset Management, said: "People need to take control of their own destiny, and whether a company scheme is available or not, they should be saving for their retirement now.
"As and when they get a chance to join a company scheme, then that is an added bonus. They can then decide to join the new plan and make their personal pension paid up or pay into both."
Lynn Graves, head of business development for corporate pensions at Scottish Widows, said: "Our research found that to meet aspirations for income in retirement, a 30-year-old saver would need to save £12,000 a year, or £1000 per month every year until retirement. In light of this, it is concerning that the amount people are willing to save each month falls well short of this target, and is decreasing year-on-year." The research also found almost half of employees (44%) were not aware how much their employer contributes and fewer than one in five (18%) would go to their employer for advice about pensions. More would go the FCA website (20%), pension providers (21%), friends and family (24%) and independent financial advisers (25%). The research says awareness remains particularly poor among those at whom the scheme is targeted, with one in five (21%) employees on an annual income of under £30,000 still not aware of the changes.
Even when putting money away, savers need to keep track of their investments.
Standard Life says three-quarters of pension savers under the age of 45 don't know what their fund is worth, and about the same proportion have no idea what income it might give in retirement.
To find a financial adviser in your area go to www.unbiased.co.uk.