Yes and no, I believe the 1st 500k in capital gains (appreciation on your house) is tax-free provided it is your primary residence for the last 3 or 5 yrs.

If this is not the case, you have 6 months to use your capital gains to buy another property before the govt takes long-term capital gains (15% tax). This is called a 1031 exchange

I am not an accountant or tax attorney so take it all with a grain of salt