| Fuel & Lubricants |
Variable |
Model at 10% of revenue in Year 1, reducing contribution margin on each job. |
Treating fuel as fixed overhead even though it rises with drilling activity. |
| Rig Maintenance & Consumables |
Variable |
Model at 8% of revenue in Year 1 as a direct margin cost tied to rig use. |
Putting maintenance below the break-even line and overstating job margin. |
| Transportation Logistics |
Variable |
Model at 5% of revenue in Year 1 because mobilization and haul activity follow project volume. |
Using one flat monthly number when logistics should move with work sold. |
| Project-Specific Insurance & Permits |
Variable |
Model at 4% of revenue in Year 1 and include it before calculating contribution margin. |
Treating permits as office overhead instead of project-linked expense. |
| Office Rent |
Fixed |
Include $5,000 per month in fixed overhead for the relevant planning range. |
Spreading rent as a percentage of revenue and hiding the monthly cash hurdle. |
| General Business Insurance |
Fixed |
Include $2,000 per month as baseline overhead before break-even volume is reached. |
Mixing general coverage with project-specific insurance and permits. |
| Payroll |
Semi-fixed |
Model by staffing plan because full-time equivalent headcount changes by year as capacity expands. |
Assuming payroll flexes smoothly with revenue instead of jumping with hires. |
| Marketing |
Semi-variable |
Use the Year 1 budget of $50,000 and $5,000 customer acquisition cost to separate planned spend from volume-driven acquisition. |
Treating the full budget as fixed without checking how many customers it must buy. |