Two of the expenses that surprised me a bit when I decided to go freelance were quarterly estimated taxes and self-employment taxes. Because taxes aren’t withheld when you’re self-employed, you have to pay quarterly estimated taxes.

Estimated taxes are a percentage of your income paid to the government based on what you think your tax liability will be for the year. Before working freelance, I visited my local H&R Block for a little advice on just how much to set aside. Given my expected income and business expenses, I was told to set 20% of my income aside for estimated taxes. This means for every $100 I make, I have to set $20 aside for taxes.

You can pay estimated taxes by sending a check to the IRS, or electronically online. If you pay estimated taxes online, you can even pay monthly, to avoid a large tax bill every three months. I currently pay my estimated taxes online monthly, though for the first year I freelanced, I paid quarterly by check.

Self-employment taxes. When you work for a corporation, and they withhold taxes, they also pay a portion of your social security and other taxes. When you work for yourself, you’re picking up the tab that your company normally would. These are called self-employment taxes and almost double your tax liability from what you owed while working for a corporation.

Half the total amount of your self-employment taxes can be written off when you file your personal taxes though, so be sure to ask your tax professional about that. You can also reduce your tax liability by writing off software you purchase to use for your freelancing and any new computer equipment or other office equipment you purchase for your home business. If the home office you’re using for your work is only used for work, you can also write off the rent you’d pay for that room as a business expense.

So while your tax liability practically doubles when you decide to go into business for yourself, many of these new expenses can be offset by deductions.

Some people find it difficult to separate their tax money from their spending money. I would suggest if you aren’t good at ear-marking money that you open a second savings account. In this account, you can deposit the money you’re setting aside for your taxes, and you’ll be sure not to spend it.

One last tip, if you have a high-interest online savings account, paying your estimated taxes every three months rather than every month means that money earns interest for you, not the IRS.