Northern Illinois Gas Company d/b/a Nicor Gas Company Rate Selection Guide
Nicor Gas is the largest natural gas distribution company in Illinois, serving ~2.6M customers across northern Illinois. For C&I and transportation customers, Nicor provides billing/usage access through MyAccount, the Open Access third-party portal, and Gas Exchange DBS flat-file subscriptions backed by a fully deployed AMI (2.2M meters) with daily reads.
Northern Illinois Gas Company d/b/a Nicor Gas Company Rate Schedule Comparison
| Schedule | Type | Rate | Best For |
|---|---|---|---|
| Rate 4 / 74 | Volumetric delivery (bundled / unbundled) | Customer charge + per-therm distribution (per ICC tariff); Customer Select credit −$0.0048/therm | Commercial & industrial users under 800,000 therms/yr |
| Rate 6 / 76 | Volumetric + minimum bill | $7,000/mo minimum bill (excl. gas) + per-therm distribution | Large C&I with high load factor, 800k–10M therms/yr |
| Rate 7 / 77 | Demand + volumetric | Demand charge (peak daily use) + per-therm; $25,000 (7) / $30,100 (77) min bill | Largest industrial loads ≥10M therms/yr |
| Rate 5 / 75 | Seasonal volumetric | Per-therm distribution; ≤700,000 therms/yr seasonal | Grain dryers, asphalt plants, other seasonal loads |
Market Overview
Nicor Gas distribution is regulated by the ICC. Gas supply choice is available via the Customer Select program (alternative gas suppliers serving residential and small commercial), but distribution and delivery remain with Nicor.
Need to pull your actual usage data to compare rates? See the Northern Illinois Gas Company d/b/a Nicor Gas Company Data Access Guide →
Current Rate Schedules
Nicor Gas (Northern Illinois Gas Company, Ill. C.C. No. 16 — Gas) classifies commercial and industrial customers by annual load and load factor. Rate 4 (General Service) serves C&I customers using up to 800,000 therms/yr on bundled sales service (Nicor supplies the gas). Rate 6 (Large Volume) serves customers using 800,000 therms to 10 million therms/yr, with a $7,000/mo minimum bill excluding gas commodity. Rate 7 (Large Volume) serves the largest customers (≥10 million therms/yr) and is demand-based, with a $25,000/mo minimum bill. Each bundled rate has an 'unbundled' transportation counterpart (Rate 74, 76, 77) for customers that buy gas from a third-party marketer and contract with Nicor only for delivery/storage. Distribution and customer charges are set in the ICC-filed tariff book; gas commodity costs are passed through via the monthly Purchased Gas Adjustment (PGA).
Effective: December 1, 2025 · Full Tariff Book →
| Schedule | Type | Applicability | Structure | Rate |
|---|---|---|---|---|
| Rate 4 — General Service (bundled) | Commercial/Industrial (small–mid, sales service) | C&I customers with annual use less than 800,000 therms who purchase all gas supplies from Nicor Gas. | Monthly customer charge plus per-therm distribution delivery charge; gas commodity recovered through the Purchased Gas Adjustment (PGA). Customers may instead take supply from a third-party marketer under Customer Select (paying delivery charges, a Customer Select Charge, and receiving a Transportation Service Credit). | Customer charge and per-therm distribution charge set in the ICC tariff book (Ill. C.C. No. 16). Customer Select participants receive a Transportation Service Credit of −$0.0048 per therm. Structure-only on $ delivery charge — see tariff.+ None — volumetric distribution charge only. |
| Rate 74 — General Transportation Service (unbundled) | Commercial/Industrial (small–mid, transportation) | Same customer profile as Rate 4 (under 800,000 therms/yr), but the customer arranges gas purchases from another source and contracts with Nicor for varying storage options. An 'unbundled' rate. | Monthly customer charge plus per-therm distribution/delivery charge and selectable storage charges; no Nicor gas-commodity component. Customer manages supply, nominations, and balancing. | Customer and delivery charges per the ICC tariff book; storage charges vary by selected storage level. Structure-only.+ None — volumetric delivery plus storage options. |
| Rate 6 — Large Volume General Service (bundled) | Industrial (large, sales service) | Large C&I customers with annual loads greater than 800,000 therms but less than 10 million therms and high load factors; purchase all gas from Nicor Gas. | Monthly customer charge plus per-therm distribution charge, subject to a minimum monthly bill; gas commodity via PGA. | Minimum monthly bill of $7,000 excluding gas commodity cost. Per-therm distribution charge set in the ICC tariff book.+ Effectively governed by the $7,000/mo minimum bill; per-therm distribution charge applies. |
| Rate 76 — Large General Transportation Service (unbundled) | Industrial (large, transportation) | Same profile as Rate 6 (800,000 to 10 million therms/yr) but customer buys gas from a marketer and contracts with Nicor for delivery/storage. | Customer charge plus per-therm delivery and storage charges, subject to a minimum monthly bill; no Nicor gas commodity. | Minimum monthly bill of $7,000 excluding gas commodity cost. Delivery/storage charges per ICC tariff book.+ Governed by the $7,000/mo minimum bill. |
| Rate 7 — Large Volume Service (bundled, demand) | Industrial (largest, sales service) | Nicor's largest customers with monthly use greater than 800,000 therms / annual use 10 million therms or more; purchase all gas from Nicor. | Demand-based: a demand charge based on the highest daily use in the month PLUS a distribution charge for each metered therm, subject to a high minimum monthly bill. Load-factor sensitive — Nicor analyzes whether Rate 6 or Rate 7 is more economical. | Minimum monthly bill of $25,000 excluding gas commodity cost. Demand and per-therm charges per the ICC tariff book.+ Yes — demand charge based on highest daily use in the billing month (largest distinguishing feature of Rate 7). |
| Rate 77 — Large Volume Transportation Service (unbundled, demand) | Industrial (largest, transportation) | Same profile as Rate 7 (≥10 million therms/yr) but customer buys gas from a marketer and contracts with Nicor for delivery/storage. | Demand charge (highest daily use) plus per-therm delivery and storage charges, subject to a high minimum monthly bill; no Nicor gas commodity. | Minimum monthly bill of $30,100 excluding gas commodity cost. Demand/delivery charges per ICC tariff book.+ Yes — demand charge based on highest daily use; minimum monthly bill $30,100. |
Rate Recommendations by Use Case
Large industrial gas user
Evaluate transportation service to procure gas supply directly while using Nicor for delivery.
Transportation customers gain control of commodity procurement and access daily-read DBS data for balancing.
- Subscribe to Long Flat File DBS for usage + nominations + storage
- Track nomination deadlines (1:00 PM CT day prior)
- Monitor Critical Day/OFO restrictions
Multi-site commercial portfolio
Consolidate billing/usage access across sites for benchmarking and reporting.
MyAccount multi-account management plus Open Access transcripts give bill-period usage history across sites.
- Use Open Access batch mode for bulk transcript pulls
- Maintain documented customer authorizations for audits
Energy consultant / aggregator
Access customer usage data at scale for efficiency and procurement analysis.
Open Access plus the Residential & Small Commercial Data License provide both per-account and program-level data.
- Register as supplier first (gasexch@nicorgas.com)
- Execute the data license agreement for bulk eligibility data
Small commercial cost reduction
Shop the gas commodity via Customer Select while staying on Nicor delivery.
Supplier choice can reduce commodity costs for predictable small C&I loads.
- Compare supplier offers to the Purchased Gas Adjustment
- Review contract terms and early-termination fees
Historical Rate Trends
Nicor Gas delivery rates are reset through general rate cases at the Illinois Commerce Commission (ICC). Recent cases produced large increases, and Nicor has filed serially — a pattern that has drawn scrutiny from the Citizens Utility Board (CUB) and the Illinois Attorney General.
November 1, 2025
ICC approved a ~$168 million delivery rate increase (Nicor had requested ~$309–320M; the ICC disallowed ~$97M / ~30% of the request). Authorized ROE set at 9.51% (down from 9.73%). New rates began appearing on bills in 2025–2026.
~$168M revenue increase; ROE 9.51%January 1, 2026
Nicor filed a new ~$221 million delivery rate increase request with the ICC less than two months after the prior case concluded; if approved it would add about $6/mo (~6.7%) to a typical residential bill beginning in 2027.
~$221M requested (filed; pending)January 1, 2023
Prior ICC general rate case granted Nicor approximately $223 million in additional delivery revenue.
~$223M revenue increaseOverall trend: Rising sharply — Nicor has received roughly $724M+ in cumulative rate increases since 2018 ($93M 2018, $168M 2019, $240M 2021, $223M 2023), with another $168M approved in November 2025 and a fresh $221M request filed January 2026.
Next expected change: The $221M request filed Jan 2026 (with the ICC) would, if approved, add roughly $6/mo (~6.7%) to a typical residential bill starting in 2027; C&I delivery charges would rise correspondingly. Decision expected within the ~11-month statutory ICC review window.
Cost Optimization Strategies
Because Nicor C&I bills separate a pass-through gas commodity (PGA) from controllable delivery charges — and because larger classes carry demand charges and high minimum bills — the main savings levers are correct rate-class placement, transportation/marketer supply, and load-factor / peak-day management.
Switch to transportation / Customer Select supply
For: Rate 4→74, Rate 6→76, Rate 7→77, or Customer Select
Move from a bundled sales rate (4/6/7) to its unbundled transportation twin (74/76/77) or to Customer Select, buying gas from a competitive marketer while Nicor delivers. Avoids Nicor's gas-commodity markup and can capture the −$0.0048/therm Transportation Service Credit.
Confirm correct rate class by volume and load factor
For: Rate 4/6/7 (and transportation twins)
Verify placement against annual therm thresholds (800,000 and 10 million) and load factor. A high-load-factor large user may save on Rate 6 vs demand-based Rate 7; Nicor offers a Rate 6-vs-7 analysis.
Peak-day / demand management (Rate 7/77)
For: Rate 7, Rate 77
On demand-based Rate 7/77, reduce the single highest daily therm use in the month — it sets the demand charge. Smoothing daily consumption directly lowers billed demand.
Manage storage, nominations and Critical Days
For: Rate 74/75/76/77 transportation customers
Transportation customers should size storage and nominations to actual load and comply with Critical Day directives to avoid unauthorized-use penalties billed at $6.00/therm.
To implement these strategies, you need your 15-minute interval data. Learn how to download Northern Illinois Gas Company d/b/a Nicor Gas Company interval data →
Frequently Asked Questions
How do C&I customers access Nicor Gas usage data?▾
Business customers use the MyAccount portal for billing and 13 months of monthly usage. Authorized third parties (suppliers, consultants) use the Open Access portal with a supplier ID and the account's last billed usage as a PIN, in live or batch mode.
Does Nicor Gas support Green Button or a public API?▾
No. Despite a fully deployed AMI (2.2M meters with daily reads), Nicor Gas does not publicly document Green Button Connect My Data, ESPI, or a public REST API. Programmatic access is via Open Access, Gas Exchange DBS flat files, the Nomination System/EGMS, and EDI.
What is the most granular usage data available?▾
Daily meter reads are captured by AMI. For transportation accounts, Gas Exchange DBS files deliver daily reads three times per week (Tue/Thu/Fri). MyAccount and Open Access transcripts show monthly/bill-period aggregation.
Can large C&I users buy gas from another supplier?▾
Yes. Large users can take transportation service (Rates 74-77) and procure their own gas supply, while small commercial customers can use the Customer Select program to choose an alternative gas supplier. Nicor continues to provide delivery.
How does third-party authorization work?▾
Third parties must register as a Nicor supplier/agent and hold documented customer authorization (agency agreement or LOA). Nicor conducts random audits and revokes access for violations.
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