Form 1040 Schedule A: Itemized Deductions (2017) – A Complete Guide
What Form 1040 Schedule A Is For
Schedule A is an attachment to your Form 1040 that lets you claim itemized deductions instead of taking the standard deduction. Think of it as a detailed list of specific expenses the IRS allows you to subtract from your income before calculating your taxes. The form covers seven main categories: medical and dental expenses, taxes you paid, interest you paid, gifts to charity, casualty and theft losses, job expenses and miscellaneous deductions, and other itemized deductions.
The basic question Schedule A answers is: ""Should I itemize or take the standard deduction?"" For 2017, you'll typically benefit from itemizing only if your total deductible expenses exceed your standard deduction—which was $6,350 for single filers, $12,700 for married couples filing jointly, $9,350 for heads of household, and $6,350 for married filing separately. If your itemized deductions add up to more than these amounts, filing Schedule A will lower your tax bill.
The form walks through each deduction category with specific lines where you report qualifying expenses. Medical expenses, for instance, are only deductible to the extent they exceed 7.5% of your adjusted gross income. State and local taxes, mortgage interest, and charitable contributions have their own rules and limitations. At the bottom, you add everything up to get your total itemized deductions, which you then enter on your Form 1040.
When You’d Use Form 1040 Schedule A (Including Late/Amended Returns)
You file Schedule A with your regular tax return by the April 15 deadline (or October 15 if you filed for an extension). You'll prepare and submit Schedule A at the same time you complete your Form 1040—they go together in one filing.
However, life doesn't always follow the tax calendar perfectly. If you discover after filing that you forgot to claim deductions or made errors on your Schedule A, you can file an amended return using Form 1040X. The IRS generally allows you to amend within three years from the date you filed your original return or within two years from when you paid the tax, whichever comes later. Common reasons for amending include discovering receipts for charitable donations you forgot to include, finding additional medical expenses that weren't initially tallied, or realizing you could have itemized when you took the standard deduction instead.
It's important to note that certain documentation must be obtained by your original filing deadline, even for amended returns. For example, written acknowledgments for charitable contributions of $250 or more must be in your hands by the date you file your return or the due date (including extensions), whichever is earlier. You can't go back and get these statements later to support an amended return if you didn't have them originally.
Key Rules or Details for 2017
The most fundamental rule is that you must choose between itemizing and taking the standard deduction—you cannot do both. Additionally, if you're married filing separately and your spouse itemizes, you must itemize too, even if your deductions are smaller than the standard deduction.
Medical and Dental Expenses
For medical and dental expenses, only amounts exceeding 7.5% of your adjusted gross income (AGI) are deductible. This is a significant hurdle. If your AGI is $50,000, for instance, you can only deduct medical expenses beyond $3,750. Insurance premiums paid with pre-tax dollars (like through employer cafeteria plans) don't count because they're already excluded from your taxable income.
Taxes You Paid
The ""taxes you paid"" category lets you choose between deducting state and local income taxes OR general sales taxes—not both. Most people choose income taxes, but if you made major purchases like a vehicle or lived in a state with no income tax, the sales tax option might be better. Real estate and personal property taxes are also deductible here.
Interest You Paid
Home mortgage interest is deductible, but complex limitations apply if you took out mortgages after October 13, 1987, or if you're deducting interest on loans exceeding certain amounts. Mortgage insurance premiums were extended through 2017 as a deductible item. Points paid on home loans are generally deductible over the life of the loan rather than all at once.
Charitable Contributions
Charitable contributions have percentage limits based on what you donated and to whom. Cash gifts are straightforward, but donations of property worth more than $500 require Form 8283. You must have written acknowledgment for any single contribution of $250 or more—a canceled check isn't enough.
High-Income Itemized Deduction Limits
A critical limitation affects high-income taxpayers: if your AGI exceeds $156,900 (married filing separately), $261,500 (single), $287,650 (head of household), or $313,800 (married filing jointly), your total itemized deductions may be reduced. This phaseout can significantly impact wealthy filers.
Step-by-Step (High Level)
Start by gathering documentation for all potentially deductible expenses paid during 2017. This includes medical bills and insurance statements, property tax bills, mortgage interest statements (Form 1098), charitable contribution receipts, and records of any other deductible expenses.
Next, calculate your medical and dental expenses. Add up all qualifying costs—insurance premiums (not paid with pre-tax dollars), doctors' visits, prescriptions, medical equipment, and mileage to medical appointments. Then multiply your AGI by 7.5% and subtract that amount from your total medical expenses. Only the excess is deductible.
Move to the taxes section. Decide whether to deduct state and local income taxes or general sales taxes by comparing both amounts—use either your actual receipts or the IRS's optional sales tax tables. Add your real estate taxes and any deductible personal property taxes. Don't include charges for services like trash collection or penalties for late payment.
For the interest section, enter your home mortgage interest from Form 1098. If you paid interest on mortgages not reported on Form 1098, you'll need to provide the lender's information. Add any deductible points and mortgage insurance premiums.
Calculate your charitable contributions by totaling cash donations and the fair market value of property donations. Make sure you have the required documentation—written acknowledgments for gifts of $250 or more, and Form 8283 for property donations exceeding $500.
Add up any casualty or theft losses, unreimbursed employee expenses (which must exceed 2% of your AGI), tax preparation fees, and other qualifying miscellaneous expenses. These sections often provide smaller deductions but shouldn't be overlooked.
Finally, total all your deductions. If your AGI exceeds the threshold for your filing status, you may need to use the Itemized Deductions Worksheet to calculate a reduced deduction amount. Compare your final itemized deduction total with your standard deduction to confirm itemizing is worthwhile, then transfer the amount to your Form 1040.
Common Mistakes and How to Avoid Them
One of the most frequent errors is double-deducting expenses already claimed elsewhere. For example, if you're self-employed and deducted medical insurance on Schedule C, you can't claim it again on Schedule A. Business expenses belong on business forms, not Schedule A. Always review what you've already deducted before completing this form.
Many taxpayers mistakenly try to deduct insurance premiums paid with pre-tax dollars through employer cafeteria plans. These amounts don't appear in Box 1 of your W-2 because they were already excluded from your income—deducting them again would be a double benefit the IRS doesn't allow. Only deduct premiums you paid with after-tax dollars.
Another pitfall involves reducing current-year deductions by refunds or credits you expect to receive. Don't reduce your 2017 deductions by a state tax refund you anticipate getting for 2017. Instead, you'll report any refund of prior-year state taxes as income on Form 1040, line 10 when you actually receive it.
People frequently fail to keep adequate documentation for charitable contributions. You must have a written statement from the charity for any single donation of $250 or more, obtained by your filing deadline. A canceled check alone isn't sufficient. For property donations exceeding $500, you need Form 8283 with detailed information about what you donated, when you acquired it, and its fair market value.
Many filers incorrectly include personal, living, or family expenses in miscellaneous deductions. Line 23 is for investment-related expenses and other specific categories—it's not a catch-all for everyday living costs. Similarly, sales taxes paid on items used in your business should go on business forms, not Schedule A.
Taxpayers sometimes itemize even when their total deductions are less than the standard deduction without checking the special box on line 30. If you're doing this for state tax reasons, you must check that box. Conversely, some people assume they can't itemize because their deductions seem low, but combining multiple categories might push them over the standard deduction threshold.
Finally, when determining if miscellaneous deductions are worthwhile, remember they must exceed 2% of your AGI. Many taxpayers waste time documenting small expenses that won't clear this hurdle. Focus your energy on major deductible expenses first.
What Happens After You File
Once you submit your Form 1040 with Schedule A attached, the IRS processes your return and uses your itemized deductions to calculate your tax liability. This typically happens within a few weeks if you filed electronically, or several weeks longer for paper returns. Your refund (or bill) will be based on the calculations you provided.
The IRS uses computer systems to check for mathematical errors and to match information from third-party documents like Forms W-2 and 1098 against what you reported. If they spot inconsistencies or potential issues, you may receive a notice asking for clarification or additional documentation. This doesn't automatically mean you did something wrong—sometimes it's just a routine inquiry.
Keep all your supporting documentation for at least three years from your filing date. While you don't attach receipts, mortgage statements, or charitable acknowledgments to your return, you must be able to produce them if the IRS requests them during an audit. The statute of limitations for most audits is three years, though it extends to six years if you substantially understated your income.
If you later discover an error or omission on your Schedule A, you can file Form 1040X to amend your return. This might result in additional tax owed (which you should pay promptly to minimize interest and penalties) or a refund if you overlooked deductions. Amended returns take longer to process than original returns—typically up to 16 weeks.
In some cases, claiming certain deductions may trigger closer scrutiny. Very large charitable deductions relative to income, significant casualty losses, or unusually high miscellaneous expenses might prompt the IRS to request documentation. This is why maintaining organized, detailed records is crucial.
FAQs
Can I itemize if my spouse takes the standard deduction?
If you're married filing separately and your spouse itemizes deductions, you must also itemize—you cannot take the standard deduction. This is a firm rule. However, if you're married filing jointly, you'll work together to choose whichever option gives you the better result. If you're filing separately and your spouse takes the standard deduction, you're free to choose either option based on what's best for you.
What if my itemized deductions are exactly equal to my standard deduction?
Take the standard deduction. It requires no documentation, reduces your audit risk slightly, and is simpler to prepare. You'll get the same tax result either way, so choose the easier path. The only exception might be if you're required to itemize for state tax purposes, in which case you'd file Schedule A and check the special box on line 30 indicating you're itemizing even though your deductions don't exceed the standard amount.
Do I need to attach my receipts and documentation when I file?
No, never attach receipts, acknowledgment letters, or other supporting documents to your return unless the IRS specifically instructs you to. Instead, keep all documentation in a safe place for at least three years in case the IRS requests it. The only form you might need to attach is Form 8283 if you donated property worth more than $500, or Form 2106 if you have employee business expenses.
I forgot to include some charitable contributions on my Schedule A. What should I do?
If you haven't filed yet, simply update your Schedule A before submitting. If you've already filed, you can file an amended return using Form 1040X to add the forgotten donations. Make sure you had the required written acknowledgments from the charities by your original filing deadline—you can't go back and get documentation dated after you filed to support an amended return. If the additional deductions will save you significant tax, amending is worthwhile; for small amounts, the paperwork might not be worth the modest refund.
Are property taxes I paid in 2017 for 2018 deductible on my 2017 return?
Generally, you can only deduct property taxes that were both assessed and paid in 2017. However, a special rule for 2017 allowed taxpayers to deduct 2018 real estate or personal property taxes if they were assessed in 2017 and paid in 2017. This was a one-time opportunity related to upcoming tax law changes. For typical situations, deduct property taxes in the year you actually pay them, regardless of which year they cover.
My AGI is high enough that my itemized deductions are limited. How does this affect me?
If your AGI exceeds the threshold for your filing status ($313,800 for married filing jointly in 2017), you must use the Itemized Deductions Worksheet in the Schedule A instructions to calculate a reduced deduction. The phaseout reduces your total itemized deductions by 3% of the amount your AGI exceeds the threshold, up to 80% of certain deductions. This can significantly impact high-income taxpayers and might mean itemizing provides less benefit than you'd expect from simply adding up your expenses. The worksheet walks you through the calculation step by step.
Can I claim medical expenses my insurance reimbursed me for later?
No, only unreimbursed medical expenses are deductible. If you paid a medical bill in 2017 and received an insurance reimbursement in 2017, subtract the reimbursement from your total medical expenses. If you paid the expense in 2017 but didn't receive the reimbursement until 2018, you can't deduct that expense on your 2017 Schedule A. If you deducted an expense in 2016 and received a reimbursement in 2017, you might need to report the reimbursement as income on Form 1040, line 21, depending on whether the prior deduction actually reduced your tax.
Sources: All information derived from official IRS publications: 2017 Schedule A Form, 2017 Instructions for Schedule A, and Publication 501 (2017).
