Billing my own company

I’m using ERPNext for a automotive repair shop.

When I work on the cars that the garage own, I need to bill parts and services and add them to the right account in the char of account to keep track of expenses on those cars.

What would be the easiest way to do that considering that I need to ajust inventory and bill work time.

Let say I do an oil change. I want to reduce inventory with the oil and filter used and “bill” 30 minutes of work time from my employee.

Ideas:

  1. Stock reconcillation (not great because we can scew hard time with that).
  2. Stock entry and manually selecting the variation account here. But can’t bill time there
  3. do a sales invoice and check update stock (and dont bill taxes and ajust selling price to cost price) and make payment with a new payment entry type that is linked with right account)?
  4. make sales order and delivery note but I dont see how to bill the right account for that
  5. Make journal entry (but can’t adjust inventory with that).
  6. I remember that there is an asset module where you can invoice assets. Maybe that?

You can use project module in ERPNext. Stock entry can be used to issue out the materials and timesheet can be used for billing.

The way I do it right now to adjust stock inventory is with stock entry, material issue, then manually go and select Accounting, Difference Account and manually select the right account.

This is not great.

And I can’t bill non stock items time this way.

Other solution I found is to create sales invoice, create a new payment entry type, select the right expense account, mark it as bank (because if not you can’t receive payment to this account) and proceed.

Other solution is sales invoice with journal entry.

But with all sales invoices it’s not good because I’m not creating an expanse I’m just creating a revenue and then cancel it with a payment entry from an expense account…