Why Custom Invoicing?

Create invoice templates to do things that basic BigTime templates can’t do. With custom invoicing, you control the information contained in line items—the core component of invoices. Add detailed descriptions and formulas that auto-calculate. Include conditions, so the line item executes only if the condition is met. 

This article will summarize key aspects of custom invoicing, so you can learn more about it. Then, we’ll direct you to specific articles about each feature.

Note: Custom invoicing is a Premier-level feature. However, Advanced and Premier users can import specific, pre-made custom calculators. Custom calculator creation is a BigTime service, and is priced at an hourly service rate. For more information, send an email to customer_success@bigtime.net.

Here’s an example. Per the contract, our customer gives us $10,000 as a down payment. Each time we create an invoice against the project, we create a credit for 10% of the fees. However, we want a perpetual deposit. If our balance falls below $5,000, we’ll charge another $10,000. We can capture all of these details with custom invoicing.



  • Gain control over your invoices, and the information that’s displayed on your line items. Add detailed descriptions, formulas that automatically calculate, as well as conditions to execute line items only if the condition is met.
  • Use custom invoices for any number of your invoicing needs, such as retainer-based billing, deposits and credits, discounted rates, and administrative markups.
  • Edit a custom invoice. Say you’re working on an invoice and want to update an existing formula for one of your line items. Return to the custom invoice and make your change. Then, return to your invoice draft.


Create a New Custom Invoice Calculator Template

A good place to start is to create a new custom invoice calculator template. Doing so will add it to your list of calculators. So when you’re ready to create an invoice, you’ll simply select the correct calculator, be it a custom or basic one. Notice in the image below that our custom calculator template, “Custom: T&M with Deposit,” is included with our basic templates.


Custom Invoicing Scenarios

Use custom invoices for retainer-based billing, deposits and credits, discounted rates, and administrative markups. We’ve set up several scenarios that use custom invoices. We use these scenarios to create a custom invoice with custom line items throughout this article series.


Create Line Items in a Custom Invoice Calculator

Line items are at the core of every invoice. With custom invoices, you can add and edit line items to provide the details your customer needs. Add a description and set a condition. Think of a condition as a rule: if the condition is true, then apply the line item.

Let’s take a closer look. We have a line item description, “Deposit.” Beneath it we have a condition (in red). This formula says: only add this line item if my deposit balance is less than $5,000. If you think that Term.Deposit.Balance is too wordy, then try the shorthand: x.Balance. “x” refers to whatever the line item type is.


Above all, custom invoicing gives you more control over your invoices to provide your clients with the necessary details they want, and to help keep you organized.


Import Calculators

Pro-level users can import calculators to access pre-made custom invoices, though you won’t be able to edit the calculators. Premier customers can also import pre-made calculators, and they’ll be able to edit them.

On your Configure Invoice Settings, click on the link, CHECK OUT BIGTIME’S GALLERY OF SPECIALIZED CALCULATORS.


Note: Get to your Configure Invoice Settings window by clicking INVOICING...CONFIGURE on your navigation bar, and then selecting Calculators.


Click IMPORT to import a calculator. The calculator will be added to your list of calculators on your Configure Invoice Settings window.


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