A surprising number of Americans consider freelancing to be the new American dream, but the freelance marketplace turns from good to evil as fast as the Jekyll & Hyde character in Robert Louis Stevenson’s classic novel. To make it work, freelancers need a plan.

“The ability to be more in control, have more independence and flexibility over your life, that’s a positive,” says Christine Russell, senior manager of retirement and annuities at TD Ameritrade. “But there’s a dark side.”

Six in 10 Americans say that freelancing is the new American Dream, according to a new Harris poll of 2,143 individuals, more than 400 of whom are freelancers. Respondents said freelancing is a less-stressful environment where workers can thrive, 

But financial uncertainties and a lack of benefits make it harder to engage in full-time freelancing. Moreover, freelancers find it’s far tougher to handle emergencies and plan for long-term goals, according to the research, which was sponsored by TD Ameritrade.

Indeed, 57% of those surveyed said that a marketplace driven by on-demand work is simply not sustainable in the long run. Nearly one in seven complain that it’s much harder for on-demand workers to plan for retirement.

Notably, roughly half of those freelancing also have a traditional job, according to the Harris Poll. And side hustling while still working a day-job may be the smartest course.

Balancing traditional work, while engaging in a side hustle, helps keep the freelance market’s malevolent nature in check, says Chinwe Onyeagoro, chief executive of PocketSuite, a phone application for small businesses. It can allow you to build your business without great risk, while also building savings to handle to often startling costs of going out on your own.

“If you don’t have a main gig that helps you get things like health insurance, it can be really difficult to stitch together enough income to cover all of your expenses,” she says. “If you jump in too quickly, you could be in for a shock.”

Indeed, few workers realize the full cost of going solo. The largest of these often unexpected costs:

FICA:

Workers are well-accustomed to paying income tax on their wages. But, when you are self-employed, you also must pay “employment taxes.” These are the employer’s share of Social Security and Medicare levies, dubbed FICA for the law that created the levy. Normally, workers pay half and employers pay half of the 15.2% tax. But when you’re self-employed the tax is all on you. Since no one takes it out of your wages as you go, this often comes as a miserable surprise to freelancers when filing annual tax returns.

Health Insurance:

The Affordable Care Act makes it possible for everyone — regardless of pre-existing conditions — to buy health insurance. However, the law didn’t necessarily make rates affordable. For those who earn enough to miss the government subsidies, rates range from a few hundred dollars per month to several thousand. Rates depend on age, plan and whether you’re buying individual or family coverage. Worse, most policies have substantial deductibles and co-payments. The only bright side? The premiums are tax deductible.

Paid time off:

Affording a vacation when you’re an employee is all about travel and hotel rooms. When you work for yourself, it’s all about lost income. If you don’t work, you don’t get paid. If you don’t budget for lost wages, you’ll probably need to work double-time before and after vacations just to catch up on the income you missed.

“You need to budget not only for the expense of the vacation, but the expense of the time off,” says Ameritrade’s Russell. “You may even need to schedule your vacation around times when you’re not busy.”

Retirement contributions:

When you go freelance, you not only give up the employer, you give up the “employer match” to your 401(k) plan. That often amounts to 25% to 50% of your retirement savings. Self-employed people have more retirement plan options than workers (more on this in a coming post). But no one kicks into your savings but you.

Deadbeats and late payments:

If an employer fails to remit your wages, you can call the Department of Labor and get government investigators on the case. It’s far tougher to force deadbeat clients to pay a freelance invoice. There are strategies to improve your chances of getting paid, but freelancers report that late payments are a normal part of life. Having money set aside to pay your bills in the interim is imperative. 

To be sure, these may be small prices to pay for the satisfaction of working for yourself. Some 84% of freelancers report being happy with their work, versus 77% in the traditional workforce, according to the survey.

But, experts caution that you shouldn’t give up the day job until you’ve contemplated how to handle these practical issues. In addition to budgeting for the additional costs of tax, health, vacations and health, the need for a substantial emergency fund is far greater for freelancers than it is for rank-and-file employees, says Russell. 

“When you have a good month or good quarter, you’ve got to set aside money for the times that aren’t going to be as good,” she says. “It’s absolutely imperative for freelancers to have an emergency fund.”