Where to Initiate
You can initiate an invoice comparison via the Invoice History page, the Invoice Detail or the Invoice Summary. On the Invoice History page each row has a compare button at the far right. On the Invoice Detail page, the compare button is located just above the icon tray. On the Summary view, each invoice has a button in it's icon tray.
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Invoice History

Invoice Detail

Invoice Summary

Note
You can also compare service-related invoice details via the Service Summary view.
The Invoice Compare View
Clicking the Compare button displays the Invoice Compare view. This view displays the two invoices side-by-side and indicates the difference in amount for each category as applicable.
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When you click the Compare option for the current invoice, you get a comparison of the current invoice to the next most recent invoice. When you click the Compare option for a previous invoice, you get a comparison of the selected (past) invoice to the current invoice.
Click End Compare to remove the comparison view and return to the Invoice Detail.
Selecting a Different Invoice to Compare
You can use the Down arrow next to the right side invoice to display a drop down menu for selecting a different invoice for comparison. The previous 12 months are available.
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Comparing Category Details
Clicking an invoice category (for example, Taxes) shows a detailed comparison of that category in the right panel.
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On the Summary tab:
For Recurring Charges, Non-Recurring Charges and Discounts, differences are broken out by feature.
For Taxes, differences are broken out by tax.
The Detail tab provides an additional breakdown by Service Number.
For Recurring Charges, Non-Recurring Charges and Discounts, differences are broken out by service number and feature.
For Taxes, differences are broken out by service number and tax.