Funny though that big insurance companies in Poland do not offer this kind of insurance given the number of people who rent in Poland: Rent guarantee insurance policies are very popular in the UK France Germany.
Imagine you rent a place for 1000zl a month , taking someone to court and paying ridiculous legal fees is not worth it.
My Polish friend from Warsaw will not do it...
Ive always manage to avoid such a sequence of events but it can cost a few thousand if you get a lawyer to represent you in court and deal with the case. It can take years to get your money back if the tenant has little or no declared income, but its probably best to go ahead with it as it sets an example for others. But to avoid such incidents, vet your tenants thoroughly (dont take the first one that agrees to take the flat), take a decent deposit and fall on them like a ton of bricks as soon as rent overdue.