Proration of expenses/deductions for Airbnb

Two weeks or less and you pay no income taxes

And the magic number is...14. Rent out a couch, a spare room or your whole house for a total of two weeks or less during the tax year and you'll pay nothing in federal taxes on the extra income.

One of the best Internal Revenue Service (IRS) breaks available, this tax break is sometimes known as "the Masters exemption" because so many people take advantage of it every year during the big annual golf tournament in Georgia.

It doesn't matter whether you earn $100 or $10,000 during those 14 days that you rent out space — you don't have to report the earnings on your taxes. However, to qualify, you must:

• Rent part or your entire house for no more than 14 days during the year
• Live in the house yourself for more than 14 days during the year or at least 10% of the time that you rent it to others.

One exception worth noting: Some companies that facilitate short-term rentals — like Airbnb and FlipKey — may report your rental income to the IRS no matter how many days you rent.

So, even if you qualify for the Masters exemption at the end of the tax year, you might get an IRS letter about the rental income. You'll need to prove that the amount is not taxable because you did not exceed the 14-day limit.

Renting for 15-days or more changes everything

Step over the annual 14-day limit, even by one day, and you'll be in completely different tax territory. The Masters exemption disappears, and rental income — including the amount you made in the first 14 days — becomes taxable. Your tax rate will vary depending on the total amount of income you report on your state and federal tax returns.

The bright side is that you can deduct 100% of direct rental expenses from the short-term rental income, including:

• Rental agency fees
• Credit checks
• Cleaning expenses

Other expenses, like mortgage interest and property taxes, must be split up between personal and business use of your residence.

Note, that the money you make from short-term vacation rentals is considered rental income for tax purposes even if you are a  renter  yourself and don't own the property.

Some cities and states charge occupancy taxes on short-term rentals. Although the guest usually owes the amount of this local tax, you, as the host, may have to collect and pay it. Sometimes the rental company collects and pays the local tax for you.

Additional Resources:

• 10 Tax Tips for Airbnb - HomeAway - VRBO and Vacation Rentals