How to Invoice Clients for Expenses and Reimbursables

Pass-through costs should be the easiest lines on your invoice, until they are not. Missing receipts, hidden markups or vague "misc" rows give finance teams a reason to send invoices back. Treat expenses like professional fees: documented, approved and easy to check. For a ready-made layout, see the expense invoice template or browse our other invoice templates.

Policy before purchase

Pre-approval

Large or unusual spending should be approved by email before you buy. Note the approver and date in the invoice notes.

Markups

If you add a handling fee, agree it in the contract and show it as its own line, never buried inside a lump sum. Many clients expect travel and lodging at cost.

Receipts

Keep every receipt, put a receipt or folio reference on each line, and send copies if the contract or the client's supplier policy asks for them. Redact unrelated personal data before sending.

Presenting expenses on the invoice

Group lines by category (Travel, Software, Materials), especially on multi-project invoices. Each line needs the date, supplier, business purpose, receipt reference and amount. Show tax consistently with invoice tax compliance. For foreign card charges, bill the amount on your card statement, or the converted amount your contract specifies; see currency conversion.

How should you bill mileage?

Bill mileage at the rate your contract states. Many US contracts refer to the IRS business standard mileage rate, which changed mid-year in 2026 (IRS standard mileage rates, accessed 28 October 2026):

So put the trip date on every mileage line. Worked example: a designer drives 120 miles to a client site on 12 June 2026 and another 120 miles on 14 July 2026. The June trip is 120 × $0.725 = $87.00 and the July trip is 120 × $0.76 = $91.20, so the mileage total is $178.20. Billing both trips at 76 cents would overcharge by $4.20.

The IRS rate is a federal tax figure, not a legal billing rate, so agree it with the client first. In the UK, a contract may refer to HMRC's approved mileage allowance payment rates instead; check the current figure on GOV.UK.

Do you charge VAT or sales tax on rebilled expenses?

United Kingdom. Under HMRC VAT Notice 700, section 25, you can leave a payment out of the value of your own supply as a disbursement only if every listed condition is met. These include that you paid as the client's agent, the client received and used the goods or services, the client authorised the payment and was responsible for it, the cost is itemised separately and you recover only the exact amount you paid. HMRC says this usually rules out your own travel, subsistence, phone and postage costs. Those are recharges: part of your supply, so a VAT-registered business charges VAT on them at the same rate as its fee. A cost with a markup cannot be a disbursement.

United States. Whether reimbursed expenses are taxed depends on the state and on whether your service is taxable. The Texas Comptroller, for example, says travel costs such as airfare, meals and hotels passed on to a customer in connection with a taxable service are part of the taxable sales price (Texas Comptroller publication 94-107). Check your own state's revenue department.

Worked UK example. A VAT-registered consultant bills a £2,000 fee, an £86 train fare for their own travel, and a £150 official filing fee they paid in the client's name as the client's agent, which meets every section 25 condition. VAT at 20% applies to the fee and the train fare: (£2,000 + £86) × 20% = £417.20. The £150 disbursement sits outside VAT. Total due: £2,000 + £86 + £417.20 + £150 = £2,653.20.

This is general information, not tax advice. Last reviewed 28 October 2026.

Cadence: bundled vs immediate

Some clients want monthly bundles of fees plus expenses; others need a separate expense invoice straight after travel. Match their accounts payable rhythm so balances do not age; if you invoice many clients at month-end, batch invoicing keeps expenses from drifting between months. Follow up with payment reminders when they are due.

Disputes and adjustments

If a line is challenged, your audit trail should hold the receipt and the approval. Agreed reductions belong in a credit note, not silent edits. For broader disagreements, use the disputed invoice approach: facts first, relationship second.

Protect margin

Uncapped "bill actuals" clauses invite scope creep. Cap pass-through costs or require an estimate above a set amount. If you offer discounts on fees, decide whether they apply to expenses and say so plainly.

How to bill expenses in InvoiceQuickly

On Pro, InvoiceQuickly records expenses with the amount, vendor, category, client, project and a billable flag. You select unbilled billable expenses, along with any unbilled time, into one draft invoice; each expense becomes a line at its exact amount, with a description you can edit before sending. It has no mileage log, does not store receipts and cannot attach files to an invoice. On every plan, you can also bill expenses as ordinary line items:

1. Add one line per cost, with quantity and unit price; for mileage, enter the miles as the quantity and the rate as the unit price, and put the trip date in the description.
2. Put the receipt reference in each line's description and any approval in the notes; send receipt copies separately.
3. Mind the tax rate: InvoiceQuickly applies one tax percentage to the whole invoice. If only some lines are taxable, as in the UK example above, calculate that tax yourself and enter it as its own line with the invoice tax set to 0%, or put the untaxed costs on a separate invoice.
4. Your VAT number or tax ID is copied to new invoice PDFs; check the saved IDs and PDF before sending.

The expense invoice template walks through a full example, and business expense tracking covers keeping the records that feed these lines.

Quick checklist before sending

• Receipt reference on every line, and copies ready to send if required
• Approver noted for anything above your threshold
• Tax treatment matches the rules where you and the client are
• PO or project code repeated on the expense invoice
• Mileage lines dated and billed at the rate for that date

Finance-friendly habits

Reconcile your business card weekly against what you plan to recharge, using the card statement amounts for foreign charges, so nothing surprising lands on the client invoice. Use supplier names that match the receipts to speed up the client's checks. If a receipt is lost, ask the supplier for a copy before you bill the cost. For mileage, state the rate and method you use and stick to it. Bundle small charges into incidentals under a stated cap only if the contract allows it; otherwise line-level detail builds trust.

Common reimbursable expense types

The line between a billable expense and overhead matters: costs incurred specifically for the client's project are billable if the contract allows; general business running costs are overhead.

Step-by-step: billing expenses to clients

Step 1: Set the rules in your contract

For example: "Reimbursable expenses: pre-approved travel, project-specific software and equipment hire, materials. Excluded: our standard software and office overhead. Mileage at the IRS business standard rate for the date of travel. Pre-approval required for any single expense over $500."

Step 2: Keep every receipt

The client may ask for copies, and you need them for your own tax records. For your own US tax records, IRS Publication 463 generally requires documentary evidence such as receipts for all lodging and for any other travel, gift or car expense of $75 or more; keep smaller receipts anyway if your client wants them.

Step 3: Itemize on the invoice

Weak: "Travel: $1,195." Strong: "Flight ATL to JFK, 12 April, ref. 7KQ2LM: $487.00 / Hotel, 2 nights × $280.00, folio 55120: $560.00 / Meals, 12 to 13 April, receipts M-1 to M-4: $148.00 / Total travel: $1,195.00." Itemizing reduces disputes and helps the client record the costs correctly.

Step 4: Match expenses to project phases

For larger engagements, group expenses by phase so they line up with the client's project budget.

Step 5: Invoice expenses promptly

Bill expenses soon after you incur them, ideally in the next billing cycle. The longer you wait, the harder they are for the client to verify.

Common scenarios

Solo consultant travelling for a client meeting: a pre-approved trip with flight, hotel, meals and parking, each itemized with its receipt reference and copies sent separately.

Designer buying a client-specific font licence: "Premium font licence for [project]: $250.00", at cost unless the contract allows a handling fee.

Photographer hiring specialty equipment for one shoot: bill the hire at cost, plus a separate handling-fee line only if agreed.

Subcontracted work: if your contract treats a subcontractor's work as a cost you pass through, show it as its own line and any markup separately; if you simply price the whole job, the subcontract is your cost and does not appear as an expense. See subcontractor invoicing.

Frequently asked questions

Should I mark up expenses?

Only if your contract or proposal says so. Many clients accept a handling fee on costs you sourced and managed, such as equipment hire or subcontracted printing, and expect travel and lodging at cost. Show any markup as a separate line with its percentage. In the UK, a marked-up cost cannot be treated as a VAT disbursement.

Can I bill expenses I incurred before the contract was signed?

Only if the client agreed to them. Costs of winning the work, such as research or proposal writing, are normally your overhead. Once the contract is signed, bill pre-approved expenses as it allows.

How do I handle expenses across multiple clients?

Keep them separate. If one purchase covered two clients, split it on a stated basis and note the split on each invoice, so each client can match its share to the receipt.

Do I need to state the mileage rate on the invoice?

Yes. Show the miles, the rate and the trip date on each mileage line, for example "120 miles × $0.76, 14 July 2026". The 2026 IRS business rate changed on 1 July, so the date shows which rate applies.

Can InvoiceQuickly add expenses or receipts to an invoice automatically?

Expenses, only when you choose them; receipts, no. On Pro, you select which recorded billable expenses to bill, and InvoiceQuickly adds them as lines on a draft invoice you review. It cannot attach receipts, so put the receipt reference in each line and send receipt copies separately.

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Pass-through costs deserve the same rigour as your rates. Get started with InvoiceQuickly.