We outprocessed our house on the 31st handed over keys signed the paper work and got our deposit back minus 50 euro. On the 1st landlord was automatically paid Aprils rent because we forgot to stop the allotment. Went to housing and they told us to just ask landlord for the money back. Husband went to meet with him and he tryd to give just 900 euro of 1400 euro back saying the rest he wanted to keep for damages to the house! Is this legal? 

No. Absolutely illegal. 

Beer or urlaub money! 

He cant just keep the money without a written estimate that confirms the supposed damages to their property! If you filled out a closing inspection checklist and he signed off on it without annotating any damages, he cannot keep the rest of your money. However, if you signed off on damages to the property and took on responsibility for them, then he has to get an estimate of the damages and give that to you and keep only the amount of the estimate to fix it. I hopes this helps. Good luck! I hope everything works out for you!