Why this bill changed

INV-2025-12-088210 · Navasota ISD — Transportation Barn · Dec 2025

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Your December bill is $171.80 higher than your November bill.

Most of the difference is colder weather — your heating ran more. You used 822 therms this period against 504 in November.

Nov 2025$311.52
Weather+$99.15
Usage beyond weather+$58.52
Gas cost+$14.13
Dec 2025$483.32

Charges and taxes for the period; any previous balance is not part of the change.

What to say

A talk track — the caller sees the same explanation in the portal

“Your December bill is $171.80 higher than your November bill. Most of the difference is colder weather — your heating ran more.”
“It was 51% colder than last month, and gas heating follows the cold — your usage line tracks the weather line on the chart.”
“Even allowing for the cold, you used about 118 therms more than usual. Has anything changed — thermostat, a new appliance, guests? We can send someone to do a free safety check.”
“If this bill is hard right now, budget billing would make it about $225.00 every month, or we can spread this one out.”

Each cause, in words

3Largest first — what the customer reads in the portalExpand

+$99.15
Colder weather
This period had 486 heating degree days against 322 — 51% colder. At the same gas per degree of cold, that alone is about 199 therms more.
+$58.52
Usage beyond the weather
Even allowing for the cold, you used about 118 therms more than your home usually does. Common causes: a higher thermostat, a new gas appliance, guests, or a leak. If you ever smell gas, leave and call (979) 555-0199 from outside.
+$14.13
Natural gas cost
The purchased gas adjustment — what we pay for the gas itself, passed through at no markup — rose from $0.3948 to $0.4120 a therm.

What to offer

Budget billing
About $225.00 a month, from the last twelve bills, settled once a year.
Letter
Payment arrangement
Spread this bill over the next few without collection activity.
Letter
Free safety checkSuggested
118 therms beyond the weather. Usually a thermostat or appliance; occasionally a leak.
Letter
Energy assistance referral
Local agencies; a pledge pauses collections while it is processed.
Letter

Emergency line for anything that smells like gas: (979) 555-0199.

Usage and weather

12 bill periods · zone heating degree days

Dec 2025 Nov 2025 Therms billed Heating degree days

Show the math

Therms, degree days and every rate, both bills — one change at a timeExpand

	Nov 2025	Dec 2025
Therms billed	504.46	821.54
… the weather alone predicts		703.84
Heating degree days	322	486
Normal degree days	290	455
Base load (summer)	113.0 th
Gas cost (PGA) / th	$0.39480	$0.41200
Weather adjustment / th	−$0.01240	−$0.01240
Customer charge	$48.00	$48.00
Distribution, first 500 th	$0.10850	$0.10850
Distribution, beyond	$0.08420	$0.08420
GRIP rider / th	$0.03070	$0.03070
Charges and taxes	$311.52	$483.32

Starting from the Nov 2025 bill, the engine re-prices it at the volume the weather predicts, then at the volume used, then swaps in this period’s gas cost, weather adjustment, and each base rate in turn. Every step is priced line by line and rounded the way the biller writes lines, so the steps add to the real difference — +$171.80 — to the cent. It reproduces every issued bill in the system exactly.