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Yes! You can use AI to fill out Form ST-105, General Sales Tax Exemption Certificate

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Form ST-105, General Sales Tax Exemption Certificate, page 1
Basic · 42/100Form Complexity Index

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What this form asks for

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Form ST-105, the General Sales Tax Exemption Certificate, is an Indiana Department of Revenue document that allows qualifying businesses to purchase goods and services without paying sales tax. To be valid, the purchaser must provide their business and identification details and specify the legal basis for the exemption, ensuring compliance with Indiana tax law. Today, this form can be filled out quickly and accurately using AI-powered services like Instafill.ai, which can also convert non-fillable PDF versions into interactive fillable forms.
Fillable fields27
Pages1
Sections12
Questions that depend on earlier answers3
Form Complexity IndexBasic, 42/100

The AI checks your answers before you download

14 checks built for this form, so a wrong date or a missing answer is caught before anyone else sees it.

Ensures a Primary Identification Number is Provided

This check verifies that the purchaser has provided at least one valid identification number as required in Section 1. The form is invalid unless either the Indiana 'TID Number' and 'LOC Number' are completed, or an alternative 'State ID Number' is provided. Failure to provide a valid ID number means the exemption cannot be processed, and the seller must charge sales tax.

Validates Indiana TID Number Format

This validation ensures the 'TID Number' field, if filled, contains exactly 10 digits. This format is specified by the Indiana Department of Revenue and is crucial for correctly identifying the registered retail merchant. An incorrect format will lead to a failed lookup in the state's database and invalidate the exemption certificate.

Validates LOC Number Format and Dependency

This check confirms that the 'LOC Number' contains exactly 3 digits and is only provided when the 'TID Number' is also filled. The LOC number is a required component of the Indiana Registered Retail Merchant’s Certificate and is meaningless on its own. Submitting a TID without a LOC, or a LOC without a TID, results in an incomplete and invalid identifier.

Requires Exclusive Purchase Type Selection

This validation ensures that the purchaser has selected exactly one option for the purchase type: either 'blanket purchase' or 'single purchase'. Selecting neither or both options creates ambiguity about the scope of the exemption. The form must be rejected if this choice is not made clearly, as it affects how the seller applies the exemption to future sales.

Requires Exclusive Exemption Reason Selection

This check verifies that the purchaser has checked one and only one box in Section 3 to indicate the reason for the exemption. The legal basis for the tax exemption is dependent on this selection, and choosing multiple reasons or none at all makes the claim invalid. If the reason is unclear, the seller is obligated to collect sales tax on the purchase.

Conditional Requirement for USDOT Number

This validation ensures that the 'USDOT Number' field is completed if the purchaser claims the 'Sales for public transportation' exemption. The USDOT number is the specific piece of evidence required to substantiate this type of claim. Failure to provide the USDOT number when claiming this exemption results in an incomplete and invalid certificate.

And 8 more checks
  • Conditional Requirement for 'Other' Exemption Explanation
  • Conditional Requirement for Federal Agency Name
  • Ensures All Certification Fields are Complete
  • Validates Certification Date is Not in the Future
  • Scans for Prohibited Purchase Items
  • Ensures Completeness of Purchaser's Full Address
  • Requires 'State of Issue' for Out-of-State IDs
  • Validates ZIP Code Format

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How to Fill Out ST-105 Online for Free in 2026

What the AI walks you through.

  1. Navigate to Instafill.ai and upload or select Form ST-105.
  2. Enter the purchaser's name and business address details in Section 1.
  3. Provide the required identification number in Section 1, such as an Indiana TID and LOC number or a State Tax ID from another state.
  4. In Section 2, specify if it is a blanket or single purchase and describe the items to be purchased.
  5. Select the appropriate reason for the exemption in Section 3, such as for resale, manufacturing, or sales to a government entity.
  6. Review all the information you have entered to ensure it is complete and accurate.
  7. Sign, date, and provide your printed name and title in Section 4 to certify the information under penalties of perjury.

Common Mistakes in Completing ST-105

The ones the AI is built to catch.

Incorrect or Incomplete Identification Number
Users often provide the wrong type of ID number or enter it incorrectly. For example, an out-of-state purchaser might leave the ID section blank, or a farmer might provide a State ID instead of the requested SSN or FID. An invalid or missing ID number will cause the seller to reject the certificate and charge sales tax, as it is a mandatory field for validating the exemption. To avoid this, carefully read the instructions for Section 1 to determine the correct ID type for your business category; AI-powered tools like Instafill.ai can help by validating number formats and guiding users to the correct field based on their entity type.
Failing to Specify Purchase Type (Blanket vs. Single)
In Section 2, purchasers frequently forget to check either the 'blanket purchase' or 'single purchase' box, making it unclear if the certificate applies to one transaction or all future qualifying purchases. An incomplete form may be rejected by the vendor, forcing them to charge sales tax until a corrected certificate is provided. Always check one of the two boxes to clearly define the scope of the exemption request.
Providing a Vague Item Description
Purchasers often write a generic description like 'parts' or 'supplies' in Section 2, which is insufficient for a seller to verify that the items qualify for the claimed exemption. This creates audit risks for the seller, who may then reject the form and charge tax to protect themselves. Be specific by listing the types of items, such as 'steel components for manufacturing' or 'cardboard packaging for resale,' to create a clear record.
Selecting the Incorrect Exemption Reason
In Section 3, a user might select an exemption category that doesn't accurately reflect their business or the item's use, such as claiming a 'resale' exemption for equipment that will be used in production. This constitutes misuse of the certificate and can lead to penalties, interest, and back taxes for the purchaser if discovered during an audit. Carefully review each exemption category and select the one that precisely matches your legal eligibility.
Omitting Required Supplemental Information for an Exemption
Certain exemptions in Section 3 require additional information that is often missed, such as providing a USDOT number for a public transportation exemption or an agency name for a federal government exemption. Failure to provide this linked information invalidates the specific exemption claim, forcing the seller to collect sales tax. Double-check if your selected exemption requires an additional ID or name and ensure it is filled in the correct space.
Missing Signature, Date, or Printed Name
It is extremely common for purchasers to leave the signature, date, printed name, or title fields in Section 4 blank. An unsigned or undated certificate is legally invalid and cannot be accepted by the seller, leading to immediate rejection and the collection of sales tax. Always complete all fields in the certification section to attest to the accuracy of the information under penalty of perjury.
Incorrectly Formatting the Indiana TID and LOC Numbers
Indiana-based purchasers often enter their Taxpayer Identification Number (TID) and Location Code (LOC) incorrectly, as the form requires a specific 10-digit TID and 3-digit LOC. Users may transpose digits, omit numbers, or enter them in the wrong fields, which prevents the seller from verifying the purchaser's registration. To prevent this, copy the numbers exactly as they appear on your certificate; using a tool like Instafill.ai can help auto-populate and format these numbers correctly.
Claiming Exemption for Prohibited Purchases
The form explicitly states it cannot be used for the purchase of Utilities, Vehicles, Watercraft, or Aircraft, but purchasers sometimes overlook this restriction. Attempting to use the certificate for these non-qualifying items is a direct violation of the form's terms and will be rejected by the seller. Misuse can also lead to penalties, so always confirm that the items you are purchasing are eligible for exemption with this specific form.
Using a DBA Instead of the Legal Business Name
Purchasers sometimes enter their 'Doing Business As' (DBA) name instead of the full legal entity name registered with the state. This can create a mismatch when the seller attempts to verify the business's tax-exempt status against official records, leading to the rejection of the form. Always use the official legal name of the business as it appears on your state registration documents to ensure a smooth validation process.
Illegible Handwriting on a Printed Form
When filling out a paper copy, purchasers often have illegible handwriting, especially in the name, address, and ID number sections. If the seller cannot accurately read the information, they cannot verify its validity, rendering the certificate useless. To avoid this, print clearly in block letters or use a fillable version of the form. Since this form is often a non-fillable PDF, a service like Instafill.ai can convert it into an interactive, fillable format to ensure all entries are typed and perfectly legible.

Frequently Asked Questions About ST-105

 

Is it really free for 7 days?
Yes. You pay $0 today. Cancel before Nov 4 and you are never charged. Keep it, and it is $19.99 a month for 5 fills of your ST-105.
Can I fill other forms too?
This plan is for your ST-105: your own AI agent fills it as often as 5 times a month. To fill other forms and upload your own, choose a Professional plan from your account.
How do I cancel?
From your account, in two clicks, any time. No email, no call.
How does the AI fill out ST-105?
You answer a few questions in plain words, or upload a document you already have. The AI reads what you give it and puts each answer into the right field of ST-105, on every page, in seconds. It checks the answers against the form's own rules, and you review and change anything before you download, print or sign.
What happens to my information?
It is encrypted in transit and at rest, and it is never used to train AI.
How complex is ST-105 to fill out?
ST-105 has a Form Complexity Index of 42 out of 100, in the basic tier: 27 fillable fields across 1 page. Instafill.ai's AI fills it in under a minute, with every field there for you to review before you download.
What is the purpose of Indiana Form ST-105?
Form ST-105, the General Sales Tax Exemption Certificate, is used by qualifying businesses and organizations to make purchases in Indiana without paying state and local sales tax. The seller keeps this form on file as proof that the sale was legally exempt from tax.
Who is eligible to use this sales tax exemption certificate?
Indiana registered retail merchants, businesses located outside Indiana, government agencies, and certain nonprofit organizations can use this form. The purchaser must be registered with the Indiana Department of Revenue or the appropriate taxing authority in their state of residence.
What is the difference between a 'blanket' and a 'single purchase' exemption?
A 'single purchase' exemption applies to one specific transaction only. A 'blanket' exemption can be used for multiple future purchases of the same type of items from the same seller, so you don't have to fill out a new form for every purchase.
I don't have an Indiana TID number. What ID number should I provide in Section 1?
If you are an out-of-state business, provide your home state's tax ID number. Specific entities like farmers, federal agencies, or nonprofits may be instructed to use their SSN or Federal Identification Number (FID) instead.
What types of purchases are not allowed to be claimed on this form?
This exemption certificate specifically cannot be used for the purchase of utilities, vehicles, watercraft, or aircraft.
What happens if I don't fill out the form completely?
The seller is required to charge sales tax if the form is not fully and correctly completed. If you pay the tax, you can file a claim for a refund directly with the Indiana Department of Revenue using Form GA-110L.
As the seller, what do I do with the completed Form ST-105?
You must keep the completed certificate on file to support the tax-exempt sale. The Indiana Department of Revenue may request to see this form during an audit to verify the exempt transaction.
I am a farmer. What ID number do I use on the form?
If you are a farmer and do not have a State Business License Number, you can enter your Federal Identification Number (FID) or Social Security Number (SSN) in the State ID Number field in Section 1.
Can I use this form for hotel stays or meals for my nonprofit?
No, the exemption for nonprofit organizations specifically states it may not be used for personal hotel rooms and meals.
I am a business from another state. Can I use my home state's exemption form in Indiana?
No, exemption statutes of other states are not valid for purchases from Indiana vendors. You must complete Indiana's Form ST-105 to claim a valid exemption on your purchase.
Can AI help me fill out Form ST-105?
Yes, services like Instafill.ai use AI to help you accurately auto-fill form fields with your saved information, which can save time and reduce errors.
How can I fill out Form ST-105 online?
You can use Instafill.ai to easily fill out your form online. Simply upload the form, and the platform will make it interactive, allowing you to type your information directly into the fields before printing or saving.
The PDF version of this form I found is not fillable. What can I do?
If you have a non-fillable PDF, you can upload it to a service like Instafill.ai. The platform can convert flat, non-fillable PDFs into interactive forms that you can easily complete on your computer.
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sales tax forms: WestRock Credit Application and Uniform Sales & Use Tax Exemption/Resale Certificate — Multijurisdiction, Form 01-339, Texas Sales and Use Tax Resale Certificate / Texas Sales and Use Tax Exemption Certification, Form DR 0024, Standard Sales Tax Receipt for Vehicle Sales, Form ST-120, New York State and Local Sales and Use Tax Resale Certificate

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tax exemption forms: WestRock Credit Application and Uniform Sales & Use Tax Exemption/Resale Certificate — Multijurisdiction, Form 01-339, Texas Sales and Use Tax Resale Certificate / Texas Sales and Use Tax Exemption Certification, 2023 Schedule IL-E/EIC, Illinois Exemption and Earned Income Tax Credit (Illinois Department of Revenue), Stipulation of Settlement With Exemption (Local Property Tax)

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