Never earning the same amount each month can also make saving difficult, which is another reason only about one in 10 self-employed workers in the UK contribute to pension schemes.
Jon Greer, head of retirement policy at Old Mutual Wealth, said: "The auto-enrolment initiative has been successful in helping more people to save for retirement.
"But the UK's five million self-employed aren't covered by auto-enrolment at all, with just 12% saving into a pension today."
Putting money aside for retirement is crucial, however, whatever your job. That's why we have come up with a five-step action plan for the millions of self-employed Britons with no retirement savings in place.
1. Ensure you qualify for the full State Pension
Self-employed workers are entitled to the State Pension in the same way as anyone else.
The level of the payments you receive will depend on your National Insurance (NI) record.
You can up your contributions if you are lagging behind to ensure you don't miss out. To find out more visit the government website.
2. Start saving into a pension fund today
The State Pension alone is unlikely to provide you with enough income to enjoy the retirement you want. For the current tax year, recipients receive just £159.55 per week.
So it makes sense to invest in a personal pension, with which you choose where you want your contributions to be invested from a range of funds offered by the provider.
The earlier you start, the better. It gives you more time to contribute to your savings before retirement, more time to benefit from tax relief, and more time for your savings to grow.
When you do, the provider will claim tax relief at the basic rate of tax on your behalf and add it to your pension savings.
If you're a basic-rate taxpayer, for every £100 you pay into your pension, the government will add an extra £25.
If you are a higher rate taxpayer you can claim back a further £25 for every £100 you pay in through your tax return.
3. Choose the right personal pension for you
There are three types of personal pension available: ordinary personal pensions offered by most large providers, Stakeholder pensions that only have charges of up to 1.5%, and Self-invested personal pensions, which offer more investment options, but often have higher charges.
You may want to choose a Stakeholder pension if your income goes up and down as these schemes allow you to stop and start your contributions without being penalised.
4. Open a Lifetime Isa
You can save up to £4,000 a year in a Lifetime Isa as a lump sum or by putting in cash when you can. The state will then add a 25% bonus on top.
So if you save £1,000, you'll have £1,250 and if you save the full £4,000, you'll have £5,000. And that's before interest or growth.
The bonus is paid every year until you hit age 50. However, Lifetime Isas are only available to the under 40s.
If you are 40 or over, a pension is your only option to benefit from similar tax breaks.
5. Save as much as you can
Saving £4,000 a year into a Lifetime Isa is a good first step on the road to a comfortable retirement - if you're young enough to qualify.
But £4,000 a year is unlikely to be enough even if you are under 40, especially if you are already in your 30s.
So even if you open a Lifetime Isa account, you should still make extra contributions to a pension fund.
You can save as much as you like towards your pension each year, but there's a limit on how much will get tax relief. This is called the annual allowance, and is currently set at £40,000.
How we spend our pensions
How we spend our pensions
Figures from Saga show that the over 50s now account for the majority of money spent by Brits on travel and tourism. They have the time to spare, the money, and they are healthy enough to take on the world.
A poll from Abta found that in the wake of pension freedoms, 35% of people were considering cashing in at least part of their pension to travel. A separate study by Senior Railcard found that pensioners take an average of three holidays a year, plus two weekends away, and 17 day trips.
Research from Senior Railcard found that retirees eat out an average of three times a month. However, one in ten do so more than twice a week, and one in three people said that one of the first things they did when they retired was to go out for lunch with their friends.
Of course, just because retirees want to enjoy themselves, it doesn't mean they are happy to throw money away. The vast majority are keen to eat at lunchtimes, when a fixed lunch menu tends to be cheaper, and canny retirees are skilled at tracking down pensioner special offers too.
Figures from the Office for National Statistics show that on average nearly a fifth of the money spent by people aged 65-74 is on leisure. This includes everything from the cinema and theatre to golfing and gardening. They spent more on this than on food, energy bills and transport.
A report by Canada Life found that retirees are spending £4,279 a year on having fun - that’s more than £1,000 more than they spend on boring essentials, and is a 74% increase over the past ten years. It went on to predict that this trend was set to continue, and that pension freedoms would encourage people to spoil themselves a bit more in retirement
Pensioner property wealth is now over £850 billion, and all these family homes don’t look after themselves. The Senior Railcard survey put home renovations in the top 20 activities people got stuck into on retirement, and figures from ABTA found that almost a third of people who were considering raiding their pension pots under the new pension freedoms planned to spend the cash on their home. This seems like an eminently sensible investment - looking after what is undoubtedly their most valuable asset.
Unsurprisingly, while some pensioners are very well off indeed, others are struggling with debt. Figures from Key Retirement found that the average retiree has £34,000 of debt.
Most of this is mortgage borrowing - in many cases driven up by the number of people who unwittingly signed up to an interest-only mortgage. However, credit cards, overdrafts, and loans are also common. It’s why so many pensioners have used pension freedoms to access enough cash to pay their debts.
The day to day basics are swallowing up their fair share of pensioner cash too. On average, people aged 65-74 spend a third of their weekly income on essentials like food and bills - which is hardly living the high life.
The bank of gran and grandad has become an increasingly vital source of cash for families. According to Key Retirement, of those who release equity from their property, 21% of them use the cash to treat their children and grandchildren. This includes an average of £33,350 to help children get onto the property ladder, £6,000 to buy them a new car, £11,000 on family weddings, and £24,780 giving grandchildren a helping hand.
While retirees are quite rightly spending what they need to enjoy retirement, they are hardly all throwing caution to the wind, buying flash cars and spending the kids' inheritance.
Most expect to have something left over to pass onto their family after their death. Some 69% expect to leave property in their wills, and 75% expect to leave cash - according to Unbiased.co.uk - because while baby boomers know how to have fun - they also know how to save for the future.