if you reinvest money from sale of vacation home do you pay capital gains?

From IRS Publication 523:

http://www.irs.gov/publications/p523/

“More than one home.

If you have more than one home, you can exclude gain only from the sale of your main home. You must include in income gain from the sale of any other home. If you have two homes and live in both of them, your main home is ordinarily the one you live in most of the time during the year.

Example 1.

You own and live in a house in the city. You also own a beach house, which you use during the summer months. The house in the city is your main home.

Example 2.

You own a house, but you live in another house that you rent. The rented house is your main home.

Factors used to determine main home. In addition to the amount of time you live in each home, other factors are relevant in determining which home is your main home. Those factors include the following. Your place of employment.

The location of your family members' main home.

Your mailing address for bills and correspondence.

The address listed on your:

Federal and state tax returns,

Driver’s license,

Car registration, and

Voter registration card.

The location of the banks you use.

The location of recreational clubs and religious organizations of which you are a member."