| Retail Store Rent |
Fixed |
Load $6,000 per month into fixed overhead from Month 1 through Month 60. |
Spreading rent across each sale and making margins look too low. |
| Utilities |
Semi-variable |
Start with the $800 monthly base, then allow usage to rise as store traffic and operating hours grow. |
Treating the full bill as fixed when higher foot traffic can raise electricity, water, and internet usage. |
| Business Insurance |
Fixed |
Include $400 per month in fixed overhead for the planning range. |
Linking insurance to unit sales instead of carrying it as a store-level monthly obligation. |
| POS & Inventory Software Subscriptions |
Fixed |
Include $250 per month as fixed operating overhead. |
Forgetting subscription tools in break-even and understating monthly overhead. |
| Store Staffing |
Semi-fixed |
Model salaries in steps as full-time equivalent staffing rises for sales, authentication, marketing, and support roles. |
Making payroll fully variable even though headcount changes in blocks, not one sale at a time. |
| Authentication Costs per Sale |
Variable |
Apply the sale-linked rate to revenue, starting at 2.0% in the first year and declining to 1.0% by the mature year. |
Putting authentication into fixed overhead and missing the margin hit from each sale. |
| Payment Processing Fees |
Variable |
Apply the processing rate to sales, from 2.5% in the first year to 2.0% in the mature year. |
Ignoring card fees when calculating contribution margin. |
| Special Packaging & Shipping |
Variable |
Apply the sale-linked rate, starting at 3.0% in the first year and falling to 2.0% in the mature year. |
Treating packaging and shipping like fixed overhead instead of order-driven spend. |