The problem with selling your home isn't the income tax on the gains. That would be new money you have. The problem is that the closing costs are very high and that you have to pay yearly property taxes on it whether or not you are selling it.
In NYS, you would lose 2% for selling a home in transfer tax (of the value not the gain); and then if you are financing another home 1.25% of the mortgage value. So right there you've lit 3% of the two transactions on fire. That doesn't even count the non-government fees like commissions, attorneys (for you and the bank), title insurance, etc. that eat quickly eat up many thousands of dollars.
Income tax on the gains tends to be bigger than these if you hold on to a property a while in a hot market. 20% of 400,000 is much bigger than 2% of 1,000,000 if you buy at 600,000 and sell at a million for example.
In NYS, you would lose 2% for selling a home in transfer tax (of the value not the gain); and then if you are financing another home 1.25% of the mortgage value. So right there you've lit 3% of the two transactions on fire. That doesn't even count the non-government fees like commissions, attorneys (for you and the bank), title insurance, etc. that eat quickly eat up many thousands of dollars.