Invoice clients for software engineering, architecture design, and technical consulting. Clean invoices from Tidybill.
A software engineer invoice is a billing document for engineering work that encompasses system design, coding, code review, technical architecture, and problem-solving across a wide range of software projects. Unlike more specialised developer invoices, software engineering work often spans multiple layers of a system and includes higher-level technical thinking such as architecture design, scalability planning, and engineering process improvements. Software engineers frequently bill on a day rate or hourly basis, though project-based and retainer models are also common. Contract software engineers embedded in product teams typically invoice weekly or bi-weekly against a timesheet. Clear documentation of work completed, systems touched, and technical outcomes helps clients justify the engineering spend internally. Senior engineers providing technical leadership or architecture reviews often invoice at a separate, higher consulting rate than hands-on coding work.
| Service | Typical Rate | Unit |
|---|---|---|
| Software engineering (day rate) | 600 | day |
| Software engineering (hourly) | 80 | hour |
| Technical architecture review | 1200 | project |
| Code review and audit | 600 | project |
| Technical documentation | 75 | hour |
| Engineering consulting (advisory) | 150 | hour |
For embedded contractor roles, invoice weekly or bi-weekly with a timesheet attached showing dates, hours, and a brief summary of work. Invoice promptly at the end of each billing period to maintain cash flow. For project-based work, invoice at milestones. For advisory consulting, invoice after each engagement session or monthly. Always use a professional invoice rather than a simple email to maintain a clear paper trail. If you operate through an umbrella company or limited company, ensure invoices are raised from the correct legal entity.