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Job Card Automation & Mechanic Workshop Billing: Link Parts and Invoicing

Job card automation links parts and labor to the invoice: parts issued to a job and labor on the job flow onto the customer invoice. One job card becomes one accurate invoice—no missed line items or manual re-entry. That's how mechanic workshop billing captures every part and hour.

In this article

  • How job cards and parts inventory work together
  • Mechanic workshop billing: labor and parts on the invoice from the job card
  • Parts leakage prevention: the biggest mistake with job cards and invoicing
  • Step-by-step flow from job card to invoice

How do job cards and parts inventory work together?

Parts are issued from inventory "to" a job card. That does two things: it reduces stock and it attaches those parts to the job. The job card then holds the full picture: labor and parts. When you're ready to bill, you convert the job to an invoice and the system pulls in both labor and parts. No second list, no guessing what was used.

One job card → one invoice: what flows where
On the job card On the invoice
Labor (type, hours, rate) Labor line items
Parts issued to job Parts line items
Subcontractor / outwork Pass-through line items
Job notes / description Invoice narrative (optional)

Mechanic workshop billing: track labor and parts on the invoice from the job card

Labor is entered on the job card (type, hours, rate). When you create the invoice from the job, those labor lines are added as invoice lines. The same applies to parts: parts on the job card become line items on the invoice. So one source (the job card) drives the invoice. This is how construction and industrial equipment shops keep labor and parts in sync with what's billed.

Tip Use a single system for stock and job cards so there's no way to use parts "off the books." When parts are only available by being issued to a job, the job card becomes the definitive list for invoicing.
Issue parts to the job Parts are deducted from inventory and linked to the job. The job card shows every part used.
Record labor on the job Enter labor type, hours, and rate. Subcontractor or outwork costs go on the job too.
Convert job to invoice One action pulls all labor and parts onto the invoice. No retyping.
Review and send Office reviews the auto-populated invoice, adds any notes, and sends. Revenue matches what was done.

Parts leakage prevention: the biggest mistake with job cards and invoicing

The biggest mistake is keeping job cards and invoicing separate: writing labor and parts on the job but then typing the invoice from memory or from scribbled notes. That's where parts get dropped and revenue leaks. The fix is to never re-enter: the invoice is generated from the job card.

What goes wrong when job and invoice are separate Technicians use parts but don't log them. Office staff forget a line item when building the invoice. The customer is undercharged, stock is wrong, and you can't reconcile. One linked flow fixes all three.
Separate job and invoice vs linked (job-card-driven) invoice
Separate systems Job-card-driven invoice
Invoice built from memory or notes Invoice built from job card data
Parts often missed → revenue leakage Every part on the job is on the invoice
Stock and billing don't match Stock issued = parts billed
Double data entry, more errors Single source of truth, no re-entry

For more on closing that gap, see how to stop parts leakage in your repair shop.

Linking job cards, parts, and invoicing isn't just convenience—it's how you make sure every hour and every part turns into revenue. One job card, one accurate invoice.

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