At the end of 2017, many new tax laws were passed, changing a variety of deduction rules. Many of these changes are both significant and complicated. Click through for an introduction to some of the most important changes.

To start with, check your mortgage totals for deductibility. Interest payments on your original mortgage, up to $750,000 for joint filers and $375,000 for others — assuming the mortgage isn’t larger than the home’s purchase price and improvement costs — are deductible for most homeowners. This $750,000 cap affects homes purchased after December 14, 2017, until 2026. (The $750,000 is an overall limit on “home acquisition” mortgage debt for purposes of deducting interest on up to two homes.)

Mortgage interest on a second home is often deductible, with limitations. If you own a third home for personal purposes, the mortgage interest is not deductible. Interest on home equity loans is often deductible with some limitations.

For many taxpayers, it may be more advantageous to take the newly changed standard deductions than to itemize. If you do not itemize, you cannot take the mortgage interest tax deduction. However, if your total itemized deductions are less than the standard deduction, it will not make sense to itemize.

For mortgages taken out more than 90 days after a home purchase, your interest deduction is usually limited to the amount of the original (acquisition) mortgage plus $100,000. However, if you use the new mortgage to improve your home, you can add that amount to the deduction limit, up to the $750,000 cap for couples who are married and filing jointly and $375,000 for others.

Other Deductions to Know About

Private Mortgage Insurance: In 2018, you can no longer deduct any mortgage insurance such as private mortgage insurance (PMI) or mortgage insurance premium (MIP).

Debt Forgiveness: The Mortgage Forgiveness Debt Relief Act of 2007 was extended through 2017, allowing those who qualify to exclude from taxation up to $2 million in debt that was forgiven by a lender through a short sale, foreclosure, deed in lieu of foreclosure or debt restructuring – within limits. If you had mortgage debt discharged in 2018, but you had a written agreement entered into before January 1, 2018, your forgiven debt will not be taxable.

Property Taxes: Real estate property taxes and state and local income and personal property taxes are deductible for most tax filers up to a combined total of $10,000. If you sold or bought property during the year, you may have paid or been refunded real estate taxes without being aware of it. See your closing statement for any prorations.

Home Offices: To take a home office deduction, you must be self-employed. Second, the home office deduction can only be taken if you itemize your deductions. Lastly, the home office must be your actual office and you cannot have an office elsewhere. If you (or your family) use your home office for non-business purposes or you are not self-employed, it cannot be claimed on your tax return. To claim home-office deductions, the space must be used exclusively and regularly for business purposes by a self-employed person.

This is just an introduction to a complex financial topic. For more details on what you cannot deduct, consult a qualified financial professional.