How do you get outstanding wages that were due before the insolvency proceedings were opened?

You can apply for insolvency benefits from the employment agency as compensation for lost wages. 

Please note: there are claims that cannot be taken into account for insolvency benefits.

You can register these as insolvency claims by entering them in the insolvency table with the insolvency administrator if they arose before the insolvency proceedings were opened. You will receive forms in which you can enter your outstanding wage claims from the period before the insolvency proceedings were opened. You should also register all other claims that are not covered by the insolvency benefits with the insolvency administrator (e.g. holiday compensation).