If you don’t have the time or inclination to design your home office, hiring an interior designer could be the right step. Before you take the plunge, take these tips from the American Society of Interior Designers.

Before you sign any agreements or make any payments, ask the designers you’re most inclined to work with to provide a proposed project plan and cost estimate in writing. This is not a contract. It’s not binding to you or the designer. The main purpose for the project plan and cost estimate is to help you compare offers from different designers.

The project plan should specify what services the designer will provide and a project timetable. It should also indicate whether other professional work—such as the services of a contractor, carpenter, electrician or architect—will be needed to complete the project.

The cost estimate should specify the type of fee structure the designer uses and an approximate total for services. If the designer charges extra for other services, such as reviewing plans or attending meetings with an architect or contractor, these should be listed as well, both by type and rate.

Designers use a variety of fee structures and base their fees on variables such as geographic location, years of expertise, professional reputation and client demand. Most designers use one of the following fee structures or a combination to suit a client’s particular needs:

• Fixed fee (or flat fee): The designer identifies a specific sum to cover costs, exclusive of reimbursement for expenses. One total fee applies to the complete scope of services proposed, from conceptual development through layouts, specifications and final installation.

• Hourly fee: Compensation is based on actual time that the designer consults on a project or specific service.

• Percentage of project fee: Compensation is computed as a percentage markup on the total project cost, including furnishings and services purchased or specified on behalf of a client.

• Retainer: The client pays a sum up front to the designer for design services. The retainer is customarily paid upon signing the contractual agreement.

• Cost plus: A designer specifies materials, furnishings and services (e.g., carpentry, picture framing, etc.) at wholesale and sells to the client at the designer’s cost plus a set percentage increase, or at retail rates or slightly less, to cover the designer’s fee and services.

• Per square foot: The designer charges fees based on the square footage of the project.

Only you can decide what’s a reasonable budget for your project. If you have concerns about price, discuss them with the designer. Don’t be shy about asking the designer to help you optimize your budget.