| Office Rent |
Fixed |
Include $5,000 per month from Month 1 through Month 60 before calculating contribution margin. |
Spreading minimum rent across each unit and making break-even look too easy at low volume. |
| Payroll |
Fixed |
Treat first-year wages as fixed overhead: $655,000 per year, or about $54,583 per month. |
Mixing salaried roles with unit-level direct labor already listed in product COGS. |
| Business Insurance |
Fixed |
Carry $1,000 per month as required overhead, regardless of monthly gallon or unit output. |
Reducing insurance when sales dip, even though the monthly policy bill still lands. |
| Utilities |
Semi-variable |
Use the $1,500 monthly base as fixed, then add production-linked usage if batches increase. |
Putting all utilities into variable COGS or ignoring higher usage during heavier production runs. |
| Product Unit COGS |
Variable |
Charge raw materials, direct labor, packaging, freight inbound, and labeling per unit produced by product line. |
Using one blended unit cost before the sales mix is stable enough to support it. |
| Sales Commissions |
Variable |
Apply 4.0% of revenue in the first year, stepping down to 3.0% by the fifth year. |
Counting commissions as fixed payroll and missing margin drag as revenue grows. |
| Shipping & Handling |
Variable |
Apply 2.0% of revenue in the first year, stepping down to 1.5% by the fifth year. |
Combining outbound shipping with inbound freight and double-counting logistics expense. |
| Added Production Labor or Storage Space |
Semi-fixed |
Add only when output requires a capacity step, not for every incremental unit sold. |
Treating capacity additions like smooth variable spending instead of step changes. |