NiSource Inc. mailing address
To mail a letter to NiSource Inc., an electric & natural-gas utility serving parts of Indiana, Ohio, Pennsylvania, Virginia, Kentucky, Maryland, and Massachusetts, send it to the correspondence address at NiSource Inc., 801 East 86th Avenue, Merrillville, IN 46410-6272. NiSource is a utility holding company whose subsidiaries (including NIPSCO) deliver electricity and natural gas across seven states. This is NiSource Inc.'s publicly listed correspondence address — for billing disputes, service requests, account closures, and formal notices. It's not the address utilities use for bill-payment remittance; use the PO Box printed on your own bill for payments. Add your return address if you'd like a reply, and confirm this address on NiSource Inc.'s official contact page before anything time-sensitive.
NiSource Inc. — correspondence address
NiSource Inc. 801 East 86th Avenue Merrillville IN 46410-6272
Written correspondence — billing disputes, service requests, account closures, and formal notices. Not the separate address used for bill-payment remittance; use the payment stub or PO Box printed on your own bill for that.
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Your name
Your return address
NiSource Inc.801 East 86th AvenueMerrillville, IN 46410-6272
Your letter, printed and mailed for you.
Key facts
- This is NiSource Inc.'s correspondence mailing address, taken from the utility's own contact page.
- NiSource Inc. is an electric & natural-gas utility serving parts of Indiana, Ohio, Pennsylvania, Virginia, Kentucky, Maryland, and Massachusetts.
- Use it for letters, disputes, service requests, and formal notices — not for bill payments, which go to a separate PO Box printed on your bill.
- Include your account number and service address so the utility can find your file.
- Include your return address and a reference number so the utility can respond.
- PostPal prints your letter and mails it for you — no printer, envelope, stamps, or post office trip.
How to send your letter
- 1
Decide what your letter is for
Use this address for written correspondence — a billing dispute, a service request, an account closure, or a formal notice. If you're mailing a cheque or payment, use the remittance address printed on your own bill instead; utilities almost always route payments to a separate PO Box.
- 2
Write your letter
Include your account number, your service address (if different from your mailing address), the outcome you're looking for, and your return address so NiSource Inc. can respond.
- 3
Address it to the correspondence address
First line: NiSource Inc.. Then the street: 801 East 86th Avenue. Then the city line: Merrillville IN 46410-6272.
- 4
Send it with PostPal
Write or upload your letter to PostPal with the address above prefilled. We print it, add your return address, and mail it for you — no printer, envelope, stamps, or trip to the post office.
Common questions
What does NiSource Inc. do?
NiSource is a utility holding company whose subsidiaries (including NIPSCO) deliver electricity and natural gas across seven states. It serves parts of Indiana, Ohio, Pennsylvania, Virginia, Kentucky, Maryland, and Massachusetts. The address above is its correspondence address — the right place for account letters, disputes, and formal notices.
What is NiSource Inc.'s mailing address?
NiSource Inc., 801 East 86th Avenue, Merrillville, IN 46410-6272. This is NiSource Inc.'s publicly listed correspondence address. Confirm it on NiSource Inc.'s official contact page before anything time-sensitive — utilities occasionally change offices and PO Boxes.
Can I mail my bill payment to this address?
Not usually. This is a correspondence address for letters, not the payment-processing address most utilities use for mailed cheques. Use the remittance address or PO Box printed on your own bill for payments, and this address for everything else — disputes, service requests, and written notices.
How do I dispute a charge or file a complaint by mail?
Write a clear, dated letter explaining the charge or issue, include your account number and any supporting documents, state what resolution you're asking for, and include your return address. Mailing it creates a dated paper record, which can help if the dispute escalates.
How do I close or transfer my account by mail?
Include your account number, the closing/transfer date, your forwarding address, and a phone number in case NiSource Inc. needs to confirm details. Most utilities also offer this online or by phone, which is often faster if you're on a tight moving deadline — mail is best for a written record or when online/phone options aren't available.
How do I mail NiSource Inc. a letter without a printer?
Write or upload your letter to PostPal with the address prefilled. We print it, add your return address, and mail it for you — no printer, stamps, or post office trip needed.
Sources
Addresses verified September 2026 against official sources. Always confirm on the official site before time-sensitive filings.