Unlike professional services, which address projects on a one-time basis, managed services are an ongoing contracted engagement that is budgeted and invoiced periodically, usually monthly. A key advantage of this approach is the difference between capital investment and operational expenses. An IT department may pay more money on a monthly basis but will avoid the up-front capital investment that many in-house solutions incur. A managed service can deploy quickly, and the financing model can yield a positive return on investment (ROI) more quickly than internally funded deployments.