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Five construction billing methods: Advantages & disadvantages

Picture of a job site in New York City preparing the scaffolding | Construction billing methods | Knowify

While all contracts will stipulate timelines and requirements, the mechanisms by which contractors get paid can vary greatly. Since construction contracts take many different forms, it’s crucial to understand how different methods operate. Mainly because different billing methods will affect your cash flow and decision-making in distinct ways.

In this article, we will break down the most common construction billing methods, taking a look at the advantages and disadvantages of each method.

Fixed price

Fixed price contracts will see a contractor and client agree to a set price for all services before the project begins. If it’s decided that a project will cost $20,000, the final project will cost $20,000 (unless altered by change orders). The basic procedure will see contractors estimate how much time, labor, and materials will go into a project according to the project’s scope of work. The contractor should then prepare a well-thought-out budget that accounts for all costs that will be incurred throughout the project. From here, contractors can apply markup and submit a proposal. Once signed and finalized, the contract price is locked in for the client. 


Facilitates the bidding process

Gives more control over profitability

Pairs well when consistently job costing

Fixed price construction billing helps facilitate the bidding process since the total contract price is known from the beginning. This can help contractors plan to come in under budget, ensuring a higher profit margin by the project’s end. In addition, fixed-price contracts give contractors more control over their profitability than other methods. If a contractor’s job costs consistently and uses historical data to create accurate estimates, the more room they can leave themselves for job-level profit.


Requires high accuracy

Unforeseen changes can impact profitability

Requires accurate estimating

Any changes in labor hours or materials costs will not affect the client but will instead impact you as the contractor. Since the price is locked in ahead of time, any unforeseen changes or complications can drastically cut into profits and result in cost overruns. It’s crucial to spend the time to thoroughly estimate the major job costs (labor, materials, equipment, subcontractor costs) for fixed-price contracts to mitigate against these unexpected costs. Accuracy is critical with fixed-priced billing methods. There is a high-risk, high-reward nature to fixed-price contracts. However, the risk can be significantly reduced through skilled estimating, job costing, and bidding. 

Having a historical data set means you can adequately plan for and budget each job. Knowing the contract price upfront allows contractors to use job costing data to create precise budgets and effective markup percentages, ensuring a profitable venture.


In the cost-plus construction billing method, contractors will get paid for all expenses plus a separate percentage, or set fee, to cover profit. A cost-plus invoice will contain all costs associated with the project (i.e., materials, labor, equipment, and subcontractor costs); all costs will be accounted for and then marked up with an agreed-upon amount to ensure the contractor generates a profit. 


Great for undefined contracts


Reduced chance of overbidding

Cost-plus agreements can eliminate a certain level of risk for contractors if a project has a considerable grey area. Cost plus is often used when it’s difficult to determine a project’s final scope and cost upfront. It provides added flexibility as adjustments can be easily made since there is no clearly defined scope of work. For example, if materials and labor costs start to increase, contractors can bill the client for these increases instead of absorbing the extra costs. Not all cost-plus contracts allow this, but it can be negotiated before the project. Another benefit is the option to include a Guaranteed Maximum Price clause in the agreement, which will put a spending cap on the amount contractors can spend. This makes cost-plus contracts a budget-friendly option for contractors looking to reign in budgets. 


Can lead to disputes

Not all costs are guaranteed to be reimbursed

Lower control of job profitability

Cost-plus can lead to disputes due to the unrefined nature of the agreements. Not every cost is automatically reimbursed. Contractors must justify and prove that an expense is qualified for reimbursement. As a result, contractors must keep highly detailed records and documents to stay organized. If a contractor cannot provide adequate documentation to justify costs, it can cause serious problems. Another drawback can result from reduced cash flow as cost-plus contracts will require the contractor to front most project costs.  

Another major disadvantage is that since profit is predetermined, there is no way to increase profitability by cutting costs or working more efficiently. This lowers the amount of profit you can make since profit is tied to your project costs. Higher costs mean higher profitability. This can back a contractor into a corner in a way that a fixed-price contract would not. 

Developing accurate budgets will also be difficult since you won’t have enough project information. Lack of project information is the most significant disadvantage for cost-plus contracts. As a result, plans will not be complete, payment schedules will be unclear, and project scope will be underdeveloped. Additionally, there is no industry standard structure for cost-plus contracts. 

This can lead to confusion on terminology, terms, and conditions within the contract. While there are scenarios where a cost-plus contract can help facilitate a successful project, entering a project without key information should be done with caution and under the right circumstances.

Time & Materials 

The time and materials construction billing method is similar to cost plus in that the final cost is left undetermined should the scope of work change. Under a time and materials contract, the client and contractor will agree on the goal of a project and specify the final outcome. Once agreed upon, the contractor will establish hourly labor rates, cost of materials, and markup percentages. Payment milestones will be set, and invoicing can be done rather quickly since rates are predetermined. Material costs are generally passed directly to the client for payment, and labor is charged hourly. 

Typically a contractor will provide the client with an hourly rate for labor and an estimation of how long the project will likely take. This generally results in a rough price range for total cost. However, it’s best to negotiate for a time and materials contract that allows for material costs to be marked up. This can help boost profit margins and ensures continued profits should additional or higher quality materials need purchasing. 


Great for undefined contracts

Benefits jobs with fluctuating material prices

Doesn't require extensive estimating upfront

Time and material billing approaches can provide less risk since contractors don’t need to estimate everything up front, and they can easily invoice labor through logged hours. If you struggle to generate profit under fixed-price projects, you may want to consider time and material projects until you can consistently generate accurate estimates. Time and material contracts are often used if the scope of work or timelines are undefined. Another scenario for this type of contract is when material prices are expected to fluctuate throughout the project.


Cost can significantly exceed the original estimate

Lower control of job profitability

Requires extensive tracking

One drawback to the time and materials method is that there is no incentive to finish the project early since contractors will be paid by the hour. There is no incentive to cut costs or time since it will not generate higher profits for the contractor. If the project comes in under the estimated price range, contractors may wonder if they would have made more if it were a fixed-price contract. 

Unit price 

Under unit price construction billing, contractors will be paid for the quantity of each line item performed as measured on the job site. Contractors will provide owners with prices for each individual task or unit, and the owner will then pay for each unit expense. Unit price contracts are sometimes called “measure and pay” contracts. Unit-priced billing aims to break down a project into quantifiable parts. 

Contractors will divide all work to be done into units. From there, each unit will be estimated for the price of labor, materials, equipment, subcontractor costs, and any other miscellaneous costs that will go into each unit. This assigns a fixed rate for each unit at the start of the project. If additional work is needed at any time, the contractor can add the additional costs to the appropriate unit, and the total cost will reflect that increase. 

This can be another solid option for contractors if the scope of work needs to be clarified. If a project grows in scope, contractors can bill additional units as needed. For example, paying for certain materials, such as dirt, can be done through a unit price billing method as it can be tough to estimate the exact amount you need at the start. In this scenario, unit price billing may be the best option since paying for dirt “by the truckload” can make more sense than bulk ordering. 

Each unit price will include all job costs such as labor, material, equipment, and profit. To generate a profit, contractors need to understand the costs associated with each unit. Therefore, contractors must mark a percentage of total costs to cover profit. If the scope of work expands and more work is required, the contractor’s profit margin should stay consistent throughout all future units of work in the project. 


Straight forward billing process


Good for material-dependant projects

Since rates are fixed, it can keep the billing process straightforward. Another main advantage is that it provides flexibility as the project progresses. Suppose a project is long-term and expected to last several years. In that case, unit pricing can be highly beneficial since contractors can expand projects and tasks midway through the project and keep their rates consistent from the start. Unit pricing can make sense for material-dependent projects where the exact amount of specific materials cannot be determined ahead of time. For this reason, many large commercial construction projects take advantage of unit pricing.


Can be difficult to properly budget and plan

Requires extensive tracking

Requires extensive documentation

Although flexible, the ambiguity of unit pricing makes it challenging to properly budget and plan. Since you don’t know how a project will progress or grow, it isn’t easy to ensure that you will be profitable at the job level. Changes in schedules and timelines will also come with a changing scope of work. As a result, this will require additional paperwork to properly document what work is being performed and what additional costs are expected. Lastly, contractors may find it challenging to price units accurately. If you miss a measurement or have to go back and recalculate, your estimates can be severely off the mark. This can lead to further issues, such as delayed payments and costly remeasurements. 

AIA-style progress billing 

Progress billing will see contractors prepare and submit invoices at different project stages. This method is usually done on a percentage-of-completion basis following a payment schedule. When previously agreed-upon milestones are hit, bills are submitted. For example, a contractor may quote a job for $40,000, to be billed on a percent completion at the end of each month. At the end of the first month, with 30% of the project completed, an invoice reflecting 30% of the total ($12,000) will be issued. This billing method is common among large and long-term projects and can be combined with other methods such as fixed price and cost plus. 

Many contractors choose to follow AIA-style progress billing methods as they provide a standardized set of invoicing forms. AIA billing typically requires two specific forms: 

  • G-702 Application and Certificate for Payment: This form provides basic project information such as parties involved, timelines, original contract sum, sum of previous payments, change orders, and outstanding payments owed. 
  • G-703 Continuation Sheet: This form will provide all relevant information needed for payment applications. Its primary purpose is to support the claims made in the G-702 documents. 

These forms can be via the AIA Contract Documents website. However, most contractors will accept non-branded forms as long as they follow the same layout and structure of official AIA documents. These forms are different from a traditional invoice. They are payment applications detailing the expected amount that will be invoiced. 

The basic structure will provide a summary of the billing progress of the overall job detailing that the contractor is entitled to payment when work is completed. Other important inclusions:

  • Total contract amount 
  • Retainage 
  • Total amount billed to date
  • Current completion percentage 
  • Remaining balance owed at the completion of work 

A schedule of values is also highly recommended. A well-structured schedule of values will detail cost, level of completion, and the percentage paid for each task. Which helps contractors and subcontractors accurately monitor job progress and ensures work is progressing as planned. 

Once a schedule of values is created, materials can be purchased, and work can be started. As the project progresses, the contractor will note the percentage of completion and calculate totals. This process is straightforward, but it can become highly complex, which is why it’s recommended to use construction management software. The right software can turn this otherwise lengthy process into quick and easy procedure. 



Promotes steady cash flow

Integrates well with construction software

The main advantage of AIA-style progress construction billing is its standardized nature as it is widely used and accepted across many trades. It also promotes a steady cash flow stream, as you don’t need to wait until the end of the project to receive payments. If you use construction management software, this billing method can be extremely time efficient and ensure professional billing through an automated process. 


Disputes can arise around the percentage of work completed

Requires documentation

Only makes sense if consistently job costing

A potential disadvantage of AIA-style progress billing will arise if you do not have a sound job costing system in place. This billing style requires costs to be tracked on a detailed and consistent basis. If you don’t have an efficient way to job cost, this can complicate matters and convolute the process. Another issue that may arise is centered around disputes on the actual percentage of work completed. Another reason why it’s paramount to carefully document work and costs. 


As you can see, construction billing methods come in many different shapes and sizes; each method has pros and cons that will work better for specific use cases. Because of this, there is no one size fits all solution. Therefore, before taking on a new project, you’ll need to understand how each billing method will impact your operations and cash flow. With proper job costing and planning, however, you can take more control of your profitability no matter the method used.

To learn more about how you can get invoices out faster with unprecedented clarity and professionalism, sign-up for a quick 30-minute demo to learn more about Knowify’s invoicing tools.