# Billable expenses and markup

> Costs incurred for a customer, passed through at cost or with a markup, and never billed twice.

Section: Projects and time · Canonical: https://intubu.intuitivecapital-dai.com/docs/billable-expenses

Any expense, bill line or item receipt can be marked **billable** to a customer or project.

**Markup** is set as a percentage or a fixed amount, per line or by a default rule for that customer. Billing at cost is a choice you make, not the only option.

**The unbilled queue** (Reports → Unbilled costs) lists every billable cost not yet invoiced, by customer and project. This is one of the most reliable sources of found money in a small business: work that was done, paid for, and never charged on.

**Billed once, and only once.** When a cost reaches an invoice it is marked billed and drops out of the queue. Removing it from the invoice puts it back.

The [Bookkeeping Command Center](https://intubu.intuitivecapital-dai.com/docs/command-center) raises a work item when billable costs sit unbilled beyond your threshold, so the queue does not need remembering.