Our office has been contacted several times with questions about filing 2018 taxes in light of the changes to federal tax law contained in the Tax Reform Act of 2017. The Maryland Comptroller's Office has provided a page that answers most common questions:
"What's New for the Tax Filing Season
Itemized Deduction Limitation - The State of Maryland follows the new federal tax law treatment to suspend the itemized deduction limitation threshold (Pease Limitation). This means that high-income taxpayers are not required to reduce their itemized deductions using the itemized deduction worksheet used in prior years.
Should I take the standard deduction or itemize? - The federal tax reform of 2017 significantly raised the federal standard deduction. Under current Maryland law, if you take the standard deduction the federal level, you cannot itemize at the Maryland level. You may take the federal standard deduction, while this may reduce your federal tax liability, it may result in an increase to your Maryland income tax liability. The Comptroller’s Office encourages you to run your income tax returns under both deduction methods, and to compare the results of taking the standard deduction versus itemizing yours deductions, to see which method causes the lowest overall tax liability.
Limitation on deduction for state and local tax - Federal tax reform limited the amount you can deduct for state and local taxes. You cannot claim more than $10,000 ($5,000 for married filing separately) for state and local taxes you paid. The new federal limitation impacts your Maryland return because you must addback the amount of state income taxes you claimed as federal itemized deductions. The addback is limited to $10,000 ($5,000 for married filing separately) and is reported on line 17b of the Maryland Form 502. Maryland will accept any reasonable interpretation of the limitation reported on line 17b. A reasonable interpretation of the law includes the following example: you, a single filer, paid $8,000 in real property taxes and $4,000 in Maryland state income taxes, Maryland will accept an addback of state income tax of $2,000 on Line 17b. In this example, the real estate taxes make up $8,000 of your $10,000 limitation and only $2,000 are required to be added back as state income taxes."