By now, you probably have a stack of tax forms from employers, banks, stockbrokers, lenders and more on your desk – or more likely, the kitchen counter. For some of you, those tax forms will end up in the hands of your tax professional, the rest of you will input the information on those forms, box for box, into tax preparation software – maybe with a little swearing along the way. No matter how you plan to do your taxes this year, you likely don’t know what all of the numbers, letters and other information on those forms mean. That’s about to change. This is the third in a series of posts meant help you make sense of all of those forms.

Here’s what you should know about the form 1098, Mortgage Interest Statement:

A form 1098, Mortgage Interest Statement, is used to report mortgage interest, including points, of $600 or more paid to a lender for a mortgage.

For federal income tax purposes, a mortgage is a loan secured by your main home or second home.  It includes first and second mortgages, home equity loans, and refinanced mortgages. A home can be a house, condominium, cooperative, mobile home, boat, or similar property. It must provide basic living accommodations including sleeping space, toilet, and cooking facilities. That means that your traditional rancher qualifies – as does a yurt, a mobile home, a yacht or a vacation home.

The rules for a mortgage apply to your primary home, as well as a second home. The total amount of debt that you can use for purposes of calculating the home mortgage interest deduction for your main home and second home cannot be more than $1 million ($500,000 if married filing separately) even if you pay more than that; some exceptions apply for grandfathered debt. You can bump the number if you have qualifying home equity debt.

The $600 threshold applies separately to each mortgage but like a form 1099, it’s not impossible that your lender will issue a form 1098 to you even if you paid less than $600. This also means that you may receive more than one form 1098 if you have more than one mortgage.

There is, however, a catch: while you may claim your qualified home mortgage interest on your federal income tax return so long as you meet the criteria, you might not have a form 1098 to show for it. The Internal Revenue Service (IRS) only requires a lender to issue a form 1098 if the property that secures your mortgage is considered real property. Real property is defined for this purpose as “land and generally anything built on it, growing on it, or attached to the land.”