Interior designers get paid through some mix of service fees and markups on the goods they buy for you. The service side is usually billed hourly, as a flat fee, or as a percentage of the total project budget. The product side comes through a markup on furniture, lighting, and materials purchased through the designer’s trade accounts. Most designers layer several of these together on a single job, take a retainer upfront, and bill reimbursable expenses on top. Which combination shows up in your contract depends on the size of the project and how the designer runs their business.
Hourly Billing
Hourly is the most common structure early in a project. The designer tracks time spent on floor plans, site visits, contractor bid reviews, and sourcing, then invoices at an agreed rate. Rates depend heavily on experience and location. Newer designers working under a firm principal often bill between $75 and $150 an hour. A senior designer with a national reputation can charge $300 or more.
Most firms use time-tracking software and send invoices with line items showing exactly what was done and how long it took. That transparency is the model’s main appeal. The trade-off is that you won’t know the total cost until the project ends. If your budget has a hard ceiling, ask for a not-to-exceed cap or a range estimate before work starts. Many designers also set a minimum project fee or minimum billable hours to weed out jobs too small to justify the administrative overhead.
Flat or Fixed Fees
A flat fee gives you one number for a defined scope of work. The designer estimates the hours involved, adds a cushion for revisions, and quotes a lump sum. The contract spells out which rooms are included, how many concept presentations you get, how many rounds of revisions are covered, and which deliverables (floor plans, elevations, material palettes) come with the fee.
The risk here is scope creep. Adding a guest bathroom halfway through, or asking for a fourth revision of the living room layout, falls outside the original agreement. A well-drafted contract includes a change-order clause specifying how additions get priced, usually at the designer’s hourly rate. Flat fees work best when you know what you want and can resist expanding the project mid-stream.
Percentage of Total Project Cost
For large renovations and new construction, designers sometimes charge a percentage of the overall project budget instead of billing by the hour or item. Fees usually run between 10% and 25% of total project costs, with the percentage dropping as the budget rises. A $200,000 renovation might carry a 20% design fee. A $2 million project might land closer to 12%.
The logic is that bigger budgets mean more complexity: more subcontractors to coordinate, more selections to make, more room for expensive mistakes. The obvious concern from your side is that the designer has no built-in reason to hold costs down, since a higher project total produces a higher fee. Good contracts address this by defining the budget range upfront and requiring your written approval before any spending increase that would raise the fee.
Cost-Plus Markup on Furniture and Materials
When a designer buys furniture, lighting, fabrics, or fixtures for you, cost-plus is how they get paid for that procurement work. Designers with trade accounts buy from manufacturers and showrooms at wholesale prices the public can’t access. They then sell those items to you at a markup, usually between 20% and 35% above their cost. That margin pays for the time spent sourcing options, placing and managing orders, coordinating deliveries, and handling damage claims when something arrives broken.
How this shows up on paper varies. Some designers list the wholesale cost and the markup as separate line items. Others quote a single price per item that still comes in below retail, but you never see the underlying numbers. Neither approach is dishonest as long as the contract spells out which method the designer uses. Ask upfront, and ask whether you’re free to buy anything on your own if you find a better deal elsewhere.
Sales Tax on Purchased Goods
Designers who buy for resale hold a seller’s permit or resale certificate in most states. That lets them purchase inventory without paying sales tax at the wholesale stage, because the tax obligation shifts to the final sale to you. The designer then collects sales tax from you on the marked-up price and remits it to the state. If the paperwork isn’t in order, you can end up either paying tax twice or triggering problems for the designer. Rules on whether the design service itself is taxable vary by state: some tax only tangible goods, some tax the transfer of finished drawings, and a few tax the whole service. It’s worth confirming how your invoice will handle tax before purchasing begins.
Hybrid Structures
In practice, very few designers stick to one billing method from start to finish. A hybrid is more common. A flat fee covers the design phase (concept development, space planning, material selection), then the designer switches to hourly for project management during construction, and charges a markup on any furnishings bought through trade accounts. Another common combination pairs a flat design fee with a retainer the designer draws against for ongoing coordination.
Each phase gets billed in the way that makes sense for the work involved. Creative development is hard to bill hourly without penalizing a designer who works fast, so a flat fee fits. Construction oversight is unpredictable enough that hourly billing protects both sides. If a designer proposes a hybrid model, the contract needs to clearly mark where one fee structure ends and the next begins.
Retainers and Deposits
Almost every designer takes money before opening your project file. The payment might be called a retainer, a deposit, or a design fee, and the label matters because each behaves differently:
- A true retainer reserves the designer’s time and is drawn down as hours are billed against it. When it runs out, you replenish it.
- A deposit is a one-time payment credited toward your final invoice.
- A non-refundable design fee pays the designer for committing a slot on their calendar, and you don’t get it back if you cancel.
Amounts commonly run from a few thousand dollars for a single-room project to $10,000 or more for whole-home work. Some designers set the upfront figure as a percentage of the estimated total fee, and 50% upfront is common on smaller projects. The contract should specify whether the payment is refundable, how it gets applied to later invoices, and what happens if the project stalls. Read this clause carefully. Disputes over retainers are one of the most common sources of friction between designers and clients.
Reimbursable Expenses
On top of design fees and product markups, most contracts include a category for reimbursable expenses. These are incidental out-of-pocket costs the designer runs up specifically because of your project: mileage or parking for site visits, printing large-format blueprints, courier fees, postage, and travel costs like airfare and hotels when the project is out of town. Reimbursables are billed at cost with no markup.
The office rent, phone bill, and staff salaries are overhead built into the designer’s rates, not something you pay separately. Shipping for a specific sofa you ordered is usually billed as part of that item’s cost, not as a reimbursable. For projects that require travel, some designers negotiate a per diem instead of itemizing every meal and cab ride. Either way, the contract should list which categories of expenses are reimbursable so nothing on the invoice surprises you.
3D renderings can catch clients off guard. If the designer outsources photorealistic renderings, interior views alone can run $800 to $1,800 per image depending on complexity. Some designers include a set number of renderings in the flat fee. Others bill them as an add-on. Clarify this at the start of the design phase if visual presentations matter to you.
Invoicing and Payment Schedules
Payment schedules live in the contract and usually follow a milestone structure: a percentage at signing, another at the end of the design phase, another when purchasing begins, and a final payment at project completion. For hourly engagements, invoices typically go out monthly with detailed time logs attached. Most designers accept checks, bank transfers, and credit cards, though some pass the credit card processing fee to the client as a line item. Whether that surcharge is allowed depends on your state’s consumer protection laws.
Late payment terms vary by contract. A common structure gives you 15 to 30 days to pay each invoice, with a 1.5% monthly interest charge on overdue balances. Many contracts also give the designer the right to pause all work until outstanding invoices are cleared. That pause clause has real consequences during construction, when a two-week delay can cascade into scheduling conflicts with contractors. Paying on time is the cheapest way to keep the project moving.
What to Confirm Before You Sign
Before signing, get clear answers on the pieces that most often generate disputes later:
- Which fee structure applies to which phase of the project, and where one ends and the next begins.
- The markup percentage on purchased goods, and whether wholesale cost and markup will appear as separate line items.
- Whether the upfront payment is a retainer, deposit, or non-refundable fee, and the conditions for a refund if the project doesn’t proceed.
- How change orders are priced when you expand the scope mid-project.
- Which expenses are reimbursable and which are baked into the designer’s rates.
- The payment schedule, late-fee terms, and whether the designer can pause work for unpaid invoices.
Every one of these should be in writing before the first site visit. Verbal understandings about how billing will work are where designer-client relationships most often break down.