Filing a state tax return for a prior year may seem unnecessary, but doing so is essential, especially if you lived or worked in Indiana during the 2015 tax year. Whether you're a full-year resident, a part-year resident, or a nonresident who earned income from Indiana sources, submitting your 2015 Indiana state tax forms ensures you're in compliance with tax laws and may help you claim a refund or avoid future penalties.
Indiana’s income tax system is relatively straightforward compared to other states. For the 2015 tax year, the state reduced its individual income tax rate from 3.4% to 3.3%, giving taxpayers slight relief. However, even a small rate change can impact how much you owe or how much you're refunded—especially for individuals and small business owners managing multiple deductions, credits, or county taxes.
This guide offers clear instructions for preparing and filing your 2015 Indiana tax return, including what forms you’ll need, how to apply for refunds or payment plans, and what deadlines still matter. If you didn’t file on time or are unsure about your obligations, this article will walk you through the process step by step. It’s designed for general taxpayers, sole proprietors, and anyone who wants to confidently catch up on their 2015 Indiana filing requirements.
Not everyone is required to file a 2015 Indiana state return, but many individuals still qualify—especially those who earned income in Indiana or had taxes withheld that year. Understanding the filing requirements helps ensure you meet your obligations and claim any refund you’re due.
You must file a 2015 Indiana tax return if you:
Gross income includes all income before deductions and credits. Even if you are not required to file a tax return, you might still want to do so if state or county taxes were withheld from your income and you qualify for a refund.
You are considered a part-year resident if you moved into or out of Indiana during 2015. You must file a state return if:
Use Form IT-40PNR to allocate income between your time as a resident and nonresident.
You are required to file if you:
Residents of reciprocal states (Kentucky, Michigan, Ohio, Pennsylvania, and Wisconsin) should use Form IT-40RNR if they only earned wage income from Indiana.
You cannot mix joint and separate statuses between federal and state returns.
You may want to file even if you aren’t required if:
Several vital updates took effect during the 2015 tax year that could affect how much tax you owed—or how much of a refund you received. Understanding these changes can help you correctly prepare your state return and avoid claiming outdated or repealed benefits.
One of the most notable changes for 2015 was a reduction in Indiana’s individual income tax rate:
While a 0.1% drop may seem minor, it directly affects your state return calculation. Apply the correct income tax rate when computing what you owe.
The state introduced or updated several deductions and credits for individuals and small business owners:
As of 2015, several credits were discontinued and are no longer valid on your return:
If you claimed any of these credits on a previous year’s return, do not include them on your 2015 filing.
Indiana extended the statute of limitations for claiming a refund from two years to three years. If you're filing now, you may still be eligible for a refund if your return falls within this window.
Filing your 2015 Indiana tax return starts with selecting the correct form based on your residency status and tax situation. Correct Indiana tax forms are essential to avoid delays, incorrect processing, or missed refunds.
These forms can be downloaded directly from the Indiana Department of Revenue (DOR) website. You must report your Social Security number, income details, and applicable deductions when completing them.
Many taxpayers must also submit supporting schedules along with their primary form. Here's what they cover:
If you operate a business, you may need to file additional state forms:
Each form has its own instructions and submission deadlines. Always double-check which documents are required for your situation.
Filing your 2015 Indiana state return requires careful attention to detail. This section walks you through the process, from gathering documents to calculating your taxes and applying for credits. Whether you're filing as an individual or sole proprietor, follow these steps to ensure accuracy and compliance.
Before you begin, collect all necessary forms and records:
Having this information on hand helps you complete the application efficiently.
Indiana begins its tax calculations with your federal adjusted gross income (AGI). You must complete your federal return before filing your state forms. This ensures accurate income reporting and eligibility for offset credits or deductions.
Select the correct Indiana tax form based on your residency and income type:
Use your federal AGI to begin filling out your state form. Then complete the relevant schedules:
Each schedule includes instructions on completing and attaching it to your primary return.
Use the following formula to compute your Indiana state tax:
Indiana adjusted income × 3.3% (0.033) = State tax owed
Then, calculate your county tax using the CT-40 form and your county’s specific tax rate.
You’ll also report any underpayment penalties if you failed to submit estimated payments during the year.
Properly reporting business income is critical to avoid underreporting or compliance issues with the Indiana DOR.
After completing your 2015 Indiana state return, the next step is choosing how to submit it. Depending on your eligibility and preferences, you may file electronically or on paper. Each method has specific instructions and benefits.
E-filing is the fastest, most secure way to file your return. For 2015 returns, Indiana offered INfreefile, a no-cost online filing option for eligible taxpayers.
Note: As of 2025, INfreefile is no longer available for filing 2015 returns, but many commercial software services still allow back-year filing for a fee.
If you prefer mailing your return, follow these guidelines:
Do not staple or paperclip documents. Do not include your federal return unless specifically instructed.
All 2015 returns must have been postmarked by April 18, 2016, to be considered timely.
If you missed the original deadline, you may have filed:
Even if you filed an extension, payment was due by April 18, 2016, to avoid penalties and interest.
If your 2015 Indiana tax return shows a balance due, paying it promptly—even if you’re filing late—is essential. Indiana offers multiple payment options for individuals and small business owners. Choosing the correct method can help you avoid interest, penalties, and potential collection actions by the Department of Revenue (DOR).
You can pay your 2015 state taxes securely online through the Indiana DOR:
To submit your electronic payment, visit in.gov/dor and click “Make a Payment.”
If you choose to mail your payment:
You should include the payment with your paper return or use a payment voucher if you are mailing it separately.
Mailing address for payments:
Indiana Department of Revenue
P.O. Box 40
Indianapolis, IN 46206-0040
Keep in mind:
After you've filed your 2015 Indiana tax return, check your refund status or verify whether you still owe any taxes. Indiana offers several ways to track both your refund and outstanding balance.
To check the status of your refund, you’ll need your:
Your refund may be delayed if:
If you receive an identity verification letter, please follow the instructions promptly to prevent further delays.
If you suspect you still owe Indiana taxes:
Staying on top of your state return status helps you avoid penalties and keep your account current.
Before submitting your 2015 Indiana tax return, use this checklist to ensure you’ve included all required forms, attachments, and documentation. Missing even one item could delay your refund or result in penalties if you owe taxes.
This checklist helps reduce filing errors and ensures your tax return is processed without unnecessary delays. It also enables you to comply with Indiana DOR requirements for individuals and small businesses.
If you missed the 2015 Indiana tax return deadline, you should still file as soon as possible. Penalties and interest accrue on any unpaid taxes, and filing late may limit your eligibility for a refund. Use Form IT-40 and indicate the tax year. While you cannot avoid interest, you can reduce penalties by filing voluntarily rather than waiting for a DOR notice.
While INfreefile is no longer available for 2015 returns, some commercial providers still offer back-year e-filing for a fee. If e-filing is unavailable, you can manually complete the return using tax forms from Indiana's DOR website and mail them to the appropriate address. E-filing is faster and more accurate, but paper filing is still accepted for prior-year returns.
Taxpayers often forget valuable Indiana deductions such as the renter’s deduction (up to $3,000), the property tax deduction (up to $2,500), and the civil service annuity deduction (up to $8,000 in 2015). Other overlooked deductions include contributions to Indiana’s 529 College Savings Plan and the public school educator expense credit. Reviewing Schedule 2 and reading the official instructions can help avoid missing these opportunities.
To request an extension for your 2015 return, you could file Form IT-9 by April 18, 2016. Filing a federal extension using IRS Form 4868 also automatically extends your Indiana deadline; however, the extension applies only to filing—not payment. Any tax owed was still due by April 18 to avoid penalties. Late payments are subject to underpayment interest and additional fees.
Yes, if you filed a joint federal return, you must also file a joint Indiana state return, even if one spouse lived outside Indiana. Use Form IT-40PNR if one spouse was a nonresident or part-year resident. This form allows you to allocate income based on residency. If you filed separate federal returns, you must file separate Indiana returns to comply with state filing rules.
If you're a sole proprietor, your business income is reported directly on your personal Indiana return (usually IT-40 or IT-40PNR). You do not need to file a separate business return. However, if your business is a partnership or LLC taxed as a partnership, you must file Form IT-65. Furthermore, file any withholding (WH-1, WH-3) and sales tax (ST-103) forms separately as required.
You should keep your 2015 tax return records for at least three years from the original filing date or two years from when the tax was paid—whichever is later. This aligns with Indiana’s updated statute of limitations for requesting a refund or correcting errors. For added protection, many tax professionals recommend keeping records for seven years, especially if your return involved complex deductions or business activity.
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