General bookkeeping tracks your overall business finances. Income, expenses, bank reconciliations, accounts receivable, accounts payable. At month end you get a profit and loss statement that shows total revenue, total costs, and whether the business made or lost money. This is the foundation of business bookkeeping and gives you the baseline for tax prep and understanding overall performance.

Job costing goes a level deeper. Instead of just tracking totals, it assigns every dollar of cost to a specific project. Labor hours, materials, subcontractor invoices, equipment rental. Each expense gets tagged to a job so you can see not just whether the business is profitable, but which jobs are profitable.

The difference matters most for project-based businesses. A contractor might have a great quarter overall but lose money on two out of five projects. Without job costing, you’d never know. You might keep bidding similar work at the same margins, not realizing those jobs consistently run over.

General bookkeeping is something every business needs regardless of type. Bank accounts get reconciled, transactions get categorized, financial statements get produced. It answers “How is my business doing?” Job costing answers “Which jobs made money and which didn’t?”

Job costing requires more discipline than general bookkeeping. Every material purchase needs a job code. Labor hours need to be tracked by project. Subcontractor invoices need to be allocated correctly. The extra effort pays off when you can see exactly which projects generate profit and which ones drain it.

For contractors and service businesses, the combination of both tells you everything you need to know. General bookkeeping for the overall picture. Job costing for the project-level detail that helps you bid better, catch overruns early, and focus on the work that actually makes you money.