The cost you front for a client — and want back

You pay $300 for materials, $180 for a flight, or a $50/month software seat that exists only to serve one client. The money left your account, but it was never really your cost — you were fronting it on the client's behalf and you intend to bill it back. That's a billable expense (also called a reimbursable or pass-through cost), and handling it cleanly is the difference between an invoice that's easy to defend and books that quietly misstate both your costs and your income. This guide walks through how to record the two sides and when a markup is appropriate. (General education, not accounting advice.)

What "billable" actually means

A billable expense is a cost you incur specifically so it can be recharged to a customer. Three things have to be true for it to behave like a pass-through:

  • It's tied to a specific client or job, not your general overhead. Your office rent isn't billable; a permit you pulled for one client's project is.
  • You expect to recover it by putting it on an invoice.
  • You can document it — a receipt or vendor bill that supports the amount you charge.

The mechanics have two halves that mirror each other. When you pay the vendor, you record an expense or vendor bill and flag it as billable to a client. When you invoice that client, the flagged cost flows onto the invoice as a line item. The two events are linked: the expense going out, and the reimbursement coming back in.

The trap: don't let pass-throughs distort your margins

Here's where it goes wrong. If you record the $300 of materials as a normal expense and also book the $300 reimbursement as revenue, your profit & loss statement now shows $300 more revenue and $300 more cost than the work actually generated. Your top line is inflated by money that was never really yours, and your margin looks different than it is.

There are two defensible ways to keep this honest, and the right one depends on whether you mark the cost up:

  • Pure pass-through (no markup). You bill exactly what you paid. The cleanest treatment is to net the reimbursement against the original expense so it washes out — the cost and the recovery cancel, leaving zero effect on profit. Some businesses instead show both the expense and a matching "reimbursed expense income" line; that's acceptable too, as long as you understand the gross-up it creates and read margins accordingly.
  • Marked-up rebill. You charge the client more than you paid — say $300 of materials billed at $360. Now the cost is $300, the revenue is $360, and the $60 spread is real gross margin you earned for sourcing and managing the purchase. Here you genuinely have income, and recording both sides is correct.

The principle: a dollar of pure reimbursement is not a dollar of profit. Only the markup is.

A worked example

You're doing a project and front three costs, then rebill:

  • Materials: paid $300, billed at cost ($300). Pass-through — no margin.
  • Travel: paid $180, billed at cost ($180). Pass-through — no margin.
  • Your labor: $1,200 of billable time.

If you treat materials and travel as pure pass-throughs that net out, your P&L shows $1,200 of service revenue at full margin and the $480 of client costs washing through with no profit effect. That's an honest picture: you earned $1,200, not $1,680.

Now suppose you instead mark the materials up to $360. The extra $60 is income — you took on sourcing risk and handling — so revenue becomes $1,260 and the $300 cost stands, leaving $60 of margin on the materials on top of your labor. Same job, deliberately different economics, and the books reflect the choice rather than blurring it.

Make the rebill easy to defend

Two habits keep billable expenses clean and disputes rare:

  1. Capture the cost against the client when you pay it, not at invoice time. Flagging the vendor bill as billable the moment it posts means nothing slips through, and the cost is already attached to the right job when you go to invoice. This is the same discipline behind good expense categorization.
  2. Itemize pass-throughs on the invoice and keep the backup. A client is far more willing to pay "$300 — materials (receipt attached)" than a vague lump sum. Listing reimbursables as their own lines — separate from your service fees — also makes it obvious which charges carry a markup and which don't, which matters if the client ever questions the bill. This pairs naturally with the workflow in turning an estimate into an invoice, where approved costs flow straight onto the bill.

Watch the sales-tax and fee edges

Two details trip people up. First, sales tax on a rebilled item isn't automatic — whether a pass-through cost is taxable when you recharge it depends on your state and what the item is, so don't assume; see sales tax on invoices and confirm your local rules. Second, if the client pays by card, the processor's fee applies to the whole invoice — including the reimbursed amount — so a pure pass-through billed at exact cost can actually leave you slightly out of pocket on the fee. For frequent or large reimbursables, a small handling markup quietly covers that gap.

Hosting Books lets you flag a vendor bill or expense as billable to a client and pull it straight onto their next invoice — at cost or with a markup — so the pass-through and the rebill stay linked and your margins reflect what you actually earned.

This article is general educational information about bookkeeping and invoicing concepts and is not accounting or tax advice for your specific situation. Sales-tax treatment of rebilled costs varies by state — confirm your local rules.