Hundreds of thousands of employers, including individuals who hire nannies or gardeners, have just six months to set up pension funds for their workers or face heavy penalties.
Under the rules, known as "automatic enrolment", every worker in the country must have a pension fund set up by, and paid into, by their employer.
The scheme has been hailed as a success so far, with eight million workers signed up for pensions since 2012, but it has yet to draw in many of the smallest employers.
Supermarkets were among the first employers to comply with the scheme and other large companies have followed suit, but very small businesses, and individuals with hired help, will soon be receiving letters informing them of their requirements.
Figures released by the Department for Work and Pensions reveal there are still 400,000 businesses yet to register their staff just months before the deadline. Those who fail to comply in time could face fines totalling several thousands of pounds.
Among the employers about to receive a letter regarding auto-enrolment will be "micro employers" including families who have hired help such as a nanny or a gardener. Experts warn many of these employers may not know how to set up a pension fund and could find the letter confusing.
Sam Barton, of Smart Pension, said: "If you get that letter it's going to be scary, you will have no idea how to go about this. There is not a 'Compare The Market' for pension schemes."
The final date for most employers will be in April next year, but newer businesses or those who recently hired their first employee may have an extension.
Who do I have to provide a pension for?
The law states that almost all workers must have a pension provided for them. Employees aged between 22 and the state pension age and earning above £10,000 a year must automatically be included in the pension plan.
However, the £10,000 "trigger" can be applied monthly or weekly, depending on how frequently the employee is paid, meaning you might have to provide a pension to someone you're paying as little as £192 a week. If earnings fluctuate, you may need to repeatedly start and stop saving.
Younger and older workers have a right to "opt in" as long as they earn over £5,876, the rate at which National Insurance starts to be applied. That means if they want you to save into a pension for them, you have to do it.
People earning below that threshold can also join, but employers do not have to make a contribution.
Under current rules, employees and employers have to save 1pc on a "band" of the individual's earnings. These minimum contributions will rise to a total of 8pc (3pc of which is paid by the employer) by 2019.
As with all pension savings, tax relief is also applied.
According to Government-backed scheme Nest, a worker is someone who "works under a contract or other arrangement to perform work or services personally and is not undertaking the work as part of their own business".
Mr Barton said a simple way to see this was whether they have a PAYE code.
This means your nanny, gardener or carer could qualify, forcing you to set up and pay into a pension fund.
The DWP insists small employers which have entered auto-enrolment so far have had a positive experience, but there are still thousands yet to register.
Pensions minister Guy Opperman said: "Business owners regularly tell us that staff who feel supported by their employer are engaged and committed. With record employment and a competitive marketplace, there is no better way to demonstrate the value of your employees than by contributing towards their workplace pension."
What are my options? And how much will it cost?
If an employee is eligible for auto-enrolment businesses will have to find them a pension provider. There are several providers specialising in helping small businesses meet their auto-enrolment requirements.
Nest has promised to provide pension for any employer who asks.
Nest's Gavin Perrera-Betts said: "Whatever provider you use, you will need to set up a scheme, enrol your employee and then make regular contributions on their behalf.
"We have automated processes with a number of payroll organisations that specialise in supporting people with nannies."
There are several companies offering the same service, including Smart Pension, Now Pensions and the People's Pension.
Under the rules, providers are not allowed to charge staff more than 0.75pc a year. However, some may charge employers separately. They also vary in what investment options are available.
Employers, which remember only have to employ one member of staff to qualify, must make a "declaration of compliance" via the Pensions Regulator. The watchdog's website explains who must comply, how and the penalties for failing to do so.
What is the punishment for not signing up?
Companies failing to comply with the rules could face hefty fines.
Mr Barton said: "There's a £400 fine for not doing complying, and if you still don't comply it gets more serious and the Pensions Regulator will have a more forensic look at you. If you're just late and then you sign up and backdate the payments that will be the end of it.
"If you ignore all the letters and fail to comply then the regulator will make you backdate your payments, and fine you 100pc of the value of the payments you should have made."
Lower league football club Swindon Town were fined £22,900 last year for "repeatedly failing to comply with its automatic enrolment duties".
Speaking at the time Charles Counsell, of the Pensions Regulator, said: "This case illustrates what can happen when an employer buries their head in the sand and disregards their duties. If things aren’t going well, then talk to us; don’t ignore us."
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