Label the basis before calculating
A price can be shown before tax or including tax. Terms such as TTC, inclusive VAT or including GST identify a basis that needs checking on the source. The imported record states the known treatment. Do not add another percentage to an inclusive price simply because your country has a familiar tax rate.
Use the model’s limits
The comparison applies its entered tax percentage to the modeled energy after energy-only discount plus the modeled fixed fees. It does not implement every jurisdiction’s exemptions, separate tax bases, levy treatment or rounding rules. Where charge categories have different treatments, use already-inclusive components or a separately documented calculation.
Allow for rounding
A published tax-inclusive unit rate may be rounded before multiplication. A supplier may instead calculate tax after summing unrounded charges or use line-level rules. A small difference does not by itself demonstrate an error. Keep sufficient decimal precision and compare the actual billing rules.
Separate recurring credits
A bill rebate, subsidy or tax credit may use an eligibility rule and a base different from the tool’s generic after-tax one-time credit. Enter documented amounts only and keep the rule with the source. Do not infer eligibility or apply a national policy to every customer.
HAUSE Energy editorial team · reviewed 2026-10-26. Calculation and coverage limits are documented in the methodology.