Your NYC rent vs buy guide

This is usually the biggest question.

Buying has costs at the beginning and costs when you eventually sell. The longer you own the apartment, the more time you have to spread those costs out.

If you are fairly sure you will move again in two or three years, buying has a harder job to do. If you could stay seven, ten or more years, buying gets more time to work in your favor.

So do not enter the number of years you hope you will stay. Enter the number you realistically expect.

Our calculator needs an assumption for how much the apartment could increase in value. It is an assumption, not a prediction.

Try changing it. See what happens if the apartment barely appreciates. Then see what happens with stronger appreciation.

If buying only wins when you assume the apartment rises quickly every year, you should know that before you buy.

This is especially important with newer condos.

Some buildings have property tax exemptions that can make today's monthly taxes look unusually low. The important question is not just what the taxes are today. Ask:

• Is there a tax exemption?
• How many years are left?
• What happens when it ends?

If you plan to own for ten years and the tax benefit ends in five, your current tax bill tells you only half the story.

Look in the offering plan for the building's tax benefit information. You are looking for the program, when the benefit began, how long it lasts and what happens during the remaining years. If you cannot make sense of it, ask your attorney or advisor to show you the actual schedule.

Do not compare a beautiful $2.5 million condo with an apartment you would never actually rent.

If I do not buy this, what would I realistically rent instead?

Use that number. And remember that rent can rise too. Your current rent is not necessarily what you will pay seven years from now.

If you rent, your down payment does not disappear. You can keep and invest that money.

That is why the calculator compares more than your mortgage payment with your rent. It asks a bigger question: at the end of the period, which choice could leave me with more money?

That includes the apartment's value, your remaining mortgage, selling costs, the money you have saved along the way and the possible growth of money you did not put into the apartment.