Interior Design Contract: Project-Based Fees and Client Changes (Change Orders)

Project-based pricing can be a game-changer for freelance interior designers and design consultants—predictable revenue, clearer scope, and less time tracking billable hours. But it only works when your contract is built to handle the reality of residential projects: clients change their minds.

Paint colors get swapped. Layouts get reworked. A “quick” sofa replacement turns into a full living room redesign. Without a contract framework that defines what’s included, what triggers additional fees, and how changes are approved, project-based fees can quietly turn into unlimited revisions for a fixed price.

This guide breaks down how to structure an interior design contract around project-based fees—and how to manage client-driven changes using a design contract with change orders so you protect your time, profit, and client relationship.

Along the way, you’ll see practical clauses and best practices you can adapt into an interior design contract template, a residential interior design agreement, or an interior designer contract sample that fits your services.

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Why project-based fees are popular—and risky—without the right contract

The appeal of project-based fees

Project-based fees (also called fixed-fee or flat-fee) are common in residential interior design because they:

• Make pricing easy for clients to understand
• Reduce invoicing complexity
• Align scope milestones with design phases
• Allow you to price based on value, not hours

The hidden risk: scope creep

Scope creep happens when the client requests “small” changes that accumulate—extra meetings, additional room selections, rework of drawings, new sourcing, or re-ordering.

A project fee doesn’t automatically protect you from scope creep. Only a well-drafted residential interior design agreement does.

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Start with strong definitions: scope, deliverables, and what “done” means

If your contract doesn’t clearly define what you’re delivering, “project-based” pricing becomes a blank check.

What to define in scope (examples)

Include a section that lists, at minimum:

• Project location and spaces included (e.g., “Living Room + Entry only”)
• Design phases (concept, schematic, design development, procurement support, installation)
• Deliverables (mood board, 2D layout, 3D renderings, finish schedule, furniture plan, shopping list)
• Presentation rounds included (e.g., 1 concept + 1 refinement)
• Procurement role (advisory vs. you purchasing on client’s behalf)
• Exclusions (e.g., structural engineering, permit drawings, contractor management unless specified)

A good interior design contract template makes scope visible and measurable—so when changes arise, you can tie them back to what the client actually purchased.

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Pricing structure: how to write project-based fees that hold up

Project-based fee language should do more than list a number. It should explain what the fee covers, how it’s paid, and when additional fees apply.

Best-practice components of a project-based fee clause

Your interior designer contract sample (or your own contract) should address:

1. Total project fee (e.g., “$7,500 for design services described in Exhibit A”)
2. Payment schedule tied to milestones
   Common structures:
   • 50% retainer to start + 25% after concept approval + 25% before final deliverables
   • Or monthly progress payments
3. Retainer is non-refundable (common for reserving calendar time)
4. Late fees / suspension rights (pause work if invoices aren’t paid)
5. What happens if the project pauses (client delay clause)

Example: milestone payment approach (plain-English)

• Deposit/Retainer: reserves time and begins discovery
• Midpoint Payment: begins sourcing/drawings/revisions
• Final Payment: released before final files, procurement release, or install support

This structure is especially important for freelancers because it keeps cashflow steady and reduces your exposure if the project stalls.

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The most important section: client changes and change orders

Residential design projects change. Your contract should assume that and create a professional, repeatable system.

A design contract with change orders typically defines:

• What counts as a change
• How changes are requested
• How you price changes (hourly, fixed add-on, or revised project fee)
• Whether deadlines shift
• When the change is binding (written approval + payment)

What counts as a “change” in interior design?

Spell it out so there’s less debate later. Examples:

• Revising approved floor plans after sign-off
• Adding rooms or areas not included in scope
• Changing the design direction (style, color palette, materials) after approval
• Swapping vendor selections after ordering begins
• Additional meetings or site visits beyond what’s included
• Rework due to client-provided measurements being incorrect

Why “approval points” matter

Build checkpoints into your agreement. For example:

• Concept Approval
• Design Development Approval
• Final Selections Approval
• Procurement Authorization

Once something is approved, changes should trigger a formal process.

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How to structure change orders (so clients actually follow them)

The goal isn’t to “punish” clients—it’s to create clarity. Clients are often happy to pay for changes if they understand why and can choose to proceed knowingly.

The change order workflow you want

Your residential interior design agreement should require:

1. Written change request (email is usually fine)
2. Designer issues a change order documenting:
   • description of change
   • additional fee (or revised fixed fee)
   • timeline impact
   • any procurement impacts (restocking fees, rush shipping, etc.)
3. Client written approval (signature or written acceptance)
4. Payment before work begins (ideal) or added to next invoice (acceptable if your cashflow can support it)

Example change order fee models (pick one)

Option A: Hourly for changes (simple and flexible)

• “Changes outside the Scope are billed at $___/hour in 0.25-hour increments.”

Option B: Fixed-fee change packages (client-friendly)

• “Additional revision round: $450”
• “Add a room: starting at $1,500, scope-dependent”

Option C: Revised project fee (for major scope shifts)

• “If changes materially alter the project, Designer may issue a revised Project Fee.”

Most freelancers use a hybrid: small changes hourly or fixed add-ons; major changes trigger a revised fee.

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Protect your timeline: changes should extend deadlines

One of the biggest pain points with client changes is timing. If your contract doesn’t clearly state that approved changes extend timelines, clients may assume you’ll absorb delays.

Include language that:

• Updates schedule estimates based on approvals
• Allows you to pause work while awaiting client decisions
• Extends deadlines when changes occur

Practical tip: Make the client responsible for “approval turnaround.” Example: “Client will respond to requests for approvals within five (5) business days.”

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Procurement and ordering: where change orders get expensive fast

If you offer procurement support (or full-service purchasing), your contract must address what happens when a client changes items after ordering.

In a residential setting, changes can trigger:

• vendor restocking fees
• return shipping costs
• non-refundable custom orders
• discontinued inventory issues
• storage fees
• delays in installation

Essential procurement contract terms to include

Whether you’re using an interior design contract template or drafting from scratch, clarify:

• Who is the “purchaser of record” (you or client)
• When items are considered approved for order
• Whether you mark up or charge a procurement fee
• Responsibility for shipping, receiving, damages, claims, and storage
• How returns/changes are handled (and who pays)

Even if you don’t want to include full procurement clauses, your agreement should at least say that vendor terms control and that client changes may create non-refundable costs.

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Revisions: set a clear limit (and define what a “revision” means)

Unlimited revisions are one of the fastest ways for a project fee to become unprofitable.

Good revision language includes:

• Number of revision rounds included (e.g., 2)
• What counts as a revision (changes requested after a formal presentation)
• What doesn’t count (typo fixes, minor specification corrections)
• The cost of additional revisions (hourly or fixed)

Pro tip: Tie revisions to “presentation packages.” Example: “Two rounds of revisions per design presentation are included.”

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Handling client-caused delays (and paused projects)

Even when clients love your work, life happens: travel, budgeting, decision fatigue, contractor delays. If the project goes quiet for weeks, your calendar and revenue are affected.

Add a project pause clause:

• Define a “pause” (e.g., no client response for 14 days)
• Allow you to suspend work and adjust timelines
• Allow restarting fees if the project restarts after a long gap (e.g., re-onboarding, updated sourcing)

This is especially important when you’re juggling multiple clients and scheduling installations.

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Dispute reduction: approvals, documentation, and “written only”

A solid contract is half the protection. The other half is workflow discipline.

Document these items consistently

• Meeting notes and recap emails
• “Approval” emails for each design phase
• Change order forms and sign-offs
• A single source of truth for selections (spec sheet)

Your interior designer contract sample should support documentation by requiring changes and approvals to be in writing.

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Key clauses your interior design contract should include (project-fee + change orders)

If you’re reviewing a new interior design contract template, look for these essentials:

1. Parties & project details (address, spaces, start date)
2. Scope of services + exclusions
3. Deliverables and presentation schedule
4. Project-based fee + payment milestones + retainer
5. Change orders process (written approval, fees, timeline impacts)
6. Revisions limit + additional revision fees
7. Client responsibilities (access, decisions, contractor coordination, accurate measurements)
8. Procurement terms (if applicable)
9. Suspension / termination (for non-payment, long delays, convenience termination)
10. Intellectual property (ownership of drawings/renderings vs. license to use)
11. Limitation of liability (where enforceable) and no guarantee of contractor performance
12. Dispute resolution (mediation/arbitration/courts) + governing law

These are the building blocks of a professional residential interior design agreement designed for real-world client behavior.

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Common mistakes designers make with project-based fees (and how to fix them)

Mistake 1: Flat fee without a tight scope

Fix: Add an exhibit with deliverables and room-by-room boundaries.

Mistake 2: No “approval” milestones

Fix: Build sign-off points and tie change orders to post-approval modifications.

Mistake 3: Vague revision policy

Fix: Define revision rounds and what counts.

Mistake 4: Allowing verbal changes during calls/texts

Fix: Require written change requests and written approvals.

Mistake 5: Not pricing timeline disruption

Fix: State that changes extend timeline and may require rescheduling fees.

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Example language (educational) for a change order clause

Below is illustrative language you might see in an interior designer contract sample. Customize to your jurisdiction and services:

Changes; Change Orders. Client may request changes to the Scope of Services by written notice. Designer will provide a written change order describing the change, any additional fees, and any schedule impacts. Designer is not obligated to proceed with any change until Client has approved the change order in writing and paid any required additional deposit. Changes requested after Client’s approval of any design phase may require rework and will be treated as out-of-scope services.

Use this as a starting point—not a substitute for professional legal review.

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How this helps you sell (not just protect)

A strong contract isn’t only defensive. It can actually help you close projects:

• Clients feel safer when expectations are clear
• Change order structure makes pricing feel fair (not arbitrary)
• Milestones make the process easier to understand
• Reduced friction means better reviews and referrals

When you present your agreement confidently, it signals you run a professional design business—not a hobby.

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Final checklist: your project-based fee contract should answer these questions

Before you send your next agreement, confirm it answers:

• What exactly am I delivering, and when?
• How many revisions and meetings are included?
• What is the fee, when is it due, and is the retainer refundable?
• What happens when the client changes their mind?
• How do I document, price, and approve changes?
• What happens to deadlines when changes occur?
• Who pays vendor cancellation/return fees?

If any of those are unclear, your project fee is at risk.

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Other questions you may ask next

• What’s the best payment schedule for a project-based interior design fee?
• Should I charge hourly for procurement and project management even on a flat-fee project?
• How do I write an interior design contract for e-design (virtual design) services?
• What terms should a residential interior design agreement include for sourcing and vendor discounts?
• How do I limit liability for contractor mistakes in my interior design agreement?
• What’s the difference between a retainer, deposit, and design fee?
• How do I handle ownership and usage rights for renderings, mood boards, and drawings?
• When should I use a separate change order form vs. email approval?

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Project-based fees can be profitable and client-friendly—if your agreement anticipates change and gives you a clear, written process to manage it. If you want a faster way to generate a polished interior design contract template, a residential interior design agreement, an interior designer contract sample, or a design contract with change orders tailored to your services, you can create one using Contractable, an AI-powered contract generator: https://www.contractable.ai