How to Invoice for Reimbursable Expenses: What to Include

How to Invoice for Reimbursable Expenses

Reimbursable expenses are costs you paid out of pocket on a client's behalf, and now you need to get that money back. Travel, software licenses, subcontractors, materials, printing - these all go on the invoice, but not the same way your service fees do. Mix them up and you'll either confuse your client, trigger a dispute, or leave money on the table.

This covers how to structure a reimbursable expense invoice, what documentation to attach, how to handle markup, and what to do when a client pushes back.

What Counts as a Reimbursable Expense

A reimbursable expense is any cost you incur on behalf of your client that wasn't part of your original quoted fee. Common examples include:

• Travel costs (flights, hotels, rental cars, mileage at the IRS standard rate)
• Software or tools bought specifically for the project
• Printing, shipping, or courier fees
• Subcontractor costs passed through to the client
• Materials or supplies purchased for the job
• Parking, tolls, and per diem meals during client travel

What does not count: your regular business overhead, software you'd use regardless of this client, or your home office costs. Those belong in your service rate, not as line items on the invoice.

How to Structure the Invoice

Keep your service fees and reimbursable expenses in separate sections on the same invoice. Do not lump them together. Here's why: your service fees are income; reimbursable expenses are cost pass-throughs. Clients read invoices quickly, and if they see one big total without a breakdown, you'll get a call asking for clarification.

Section 1: Professional Services

List your hours or project deliverables here. "Brand strategy consulting - 12 hours at $150/hour - $1,800" is a clean line item. This section is your fee for work performed.

Section 2: Reimbursable Expenses

List every expense as its own line item. Do not write "Expenses - $347.22" as a single line. Break it out:

• Airfare - Chicago to Denver, March 4, 2026 - $312.00
• Hotel - Marriott Denver, March 4-5, 2026 (2 nights) - $218.40
• Uber to/from airport - $47.60
• Meals (per diem, 2 days at $75/day) - $150.00

Specific dates, vendors, and amounts give your client everything they need to approve and process the invoice without follow-up questions.

Subtotals and Total

Show a subtotal for services, a subtotal for expenses, and then a grand total. If you charge tax on services but not on reimbursements (rules vary by location - check your jurisdiction), you need separate subtotals to apply tax correctly.

Do You Need to Mark Up Expenses

Some consultants and agencies add a markup to reimbursable expenses, typically 10-20%, to cover administrative time spent managing purchases, holding receipts, and fronting the cash. This is legitimate, but you need to disclose it.

If your contract says "expenses billed at cost," do not add a markup. If your contract says "expenses plus 15% handling fee" or similar, you can add the markup and it should appear as its own line item on the invoice, not hidden inside the expense amounts.

A client who later discovers a hidden markup will feel deceived, even if the amount was small. Transparency avoids that conversation entirely.

Documentation to Attach

Attach receipts. Always. Some clients will pay without them, but if you're invoicing a company of any size, their accounting department will likely hold the payment until they have backup documentation. Attach digital copies of every receipt directly to the invoice email or upload them alongside the invoice in your invoicing software.

For mileage reimbursement, attach a mileage log with dates, start point, end point, and miles driven. The IRS standard mileage rate for 2026 is 70 cents per mile, but your client's reimbursement policy may differ from that.

For subcontractor pass-throughs, attach the subcontractor's invoice to show the actual cost paid. If you're marking it up, that should be disclosed in your contract ahead of time.

Timing: When to Invoice for Expenses

You have two options:

Invoice with the project: Add expenses to the final project invoice. Works well for short projects where all expenses are incurred before the project closes.

Invoice monthly for expenses: For ongoing retainers or long projects, send a monthly expense invoice separate from your service invoice. This keeps your cash flow healthier since you're not waiting to recover $800 in travel costs until the project ends six months from now.

Whatever you choose, set the expectation in your contract upfront. "Reimbursable expenses are invoiced monthly" or "Expenses will be included in the final project invoice" - either works, but the client should know before the invoice arrives.

Pre-Approval: The Smart Move

Before spending significant money on a client's behalf, get written approval. A quick email works: "I'll need to fly to Austin for the kickoff meeting. Flight is running about $380. Does that work within the project budget?"

That email is your protection when you invoice. If a client later says "We didn't expect this expense," you can point to the approval. Without it, you're in a he-said-she-said situation over who authorized what.

For recurring expenses on retainers, include a monthly expense cap in the contract. "Reimbursable expenses not to exceed $500/month without prior approval" is a clean way to set limits without arguing every time.

Common Disputes and How to Handle Them

"We don't reimburse meals." This is their prerogative, but it should have been in the contract. If it wasn't, negotiate. If your contract says expenses are reimbursable and doesn't exclude meals, push back calmly with documentation.

"This expense seems high." Provide the receipt. If you flew business class when economy was available for less, expect pushback. If you flew economy but happened to book during a surge, provide the receipt and explain the timing.

"We need the receipts before we can pay." Standard response from any accounting department. Get ahead of this by always attaching receipts to your initial invoice. It removes the delay entirely.

Tax Treatment of Reimbursed Expenses

Here's a common misconception: if your client reimburses you for an expense, you typically cannot also deduct that same expense on your taxes. You're being made whole, not incurring a net cost. The reimbursed amount is generally not counted as income, and you don't deduct the expense.

If you add a markup to expenses (say, $100 expense billed at $115), the $15 markup is income to you. Track this carefully and talk to your accountant about how your specific situation works in your jurisdiction. The IRS has specific rules around accountable plans that are worth understanding if expense reimbursements are a regular part of your business.

Using Invoice Templates for Expense Billing

A Word or PDF template with pre-built sections for services and expenses will save you time and reduce errors. WaffleInvoice's free Word invoice template includes separate sections you can adapt for expenses. Or use the free invoice generator to build a clean, professional invoice in a few minutes without any design work.

For ongoing clients where you invoice expenses regularly, invoicing software with line item support will save you hours every month compared to manually updating a spreadsheet or Word doc.

Set up the expense section once in your template, then duplicate it each billing cycle. Attach the receipts, send the invoice, and you're done.

Quick Reference: Expense Invoice Checklist

• Separate sections for service fees and reimbursable expenses
• Each expense as its own line item with date, vendor, and amount
• Subtotals for services and expenses shown separately
• Markup disclosed if applicable
• Receipts attached (digital copies are fine)
• Mileage log attached if claiming mileage
• Written pre-approval on file for large or unexpected expenses
• Payment terms stated clearly on the invoice

Learn more about setting payment terms that protect you: Payment Terms for Freelancers. And if expenses pile up and a client goes quiet, here's how to handle it: How to Charge a Late Fee.