Hi, Ive been looking into this recently.

Your mortgage in Germany would have to be above €50000 as below this is more hastle than it is worth for the banks. The repayments would have to be covered by the rental income minus 25% (ball park running costs) unless you can prove the running costs are below this. One bank that I spoke to offered up to 68% of the total value again so long as the repayments are covered.