over paid tax benefits in england uk?

if person was over paid tax benefits in england uk and they leave go home to poland will they be looked for in poland to repay this back

Yes..

how much time do it take? are u sure 100 per cent

Don't know but you should do the honest thing. Would probably depend on how much though

it for my sistora. she has child in uk and was in relationship with brasil man relationship broke he only pay half money

Sorry not sure what you mean.

relationship broke bad and sisto and ex received a letter say they were over paid tax he only paying half back what does happen to rest of half? if my sist in poland. do they look for money in poland back

OK, In that case it would depend on how much it was for In my opinion, but delphiandomine might know more on this than I do.

If it is from HMRC then they normally will chase people in a different country, however if benefit agency they are so useless I would be surprised but again will depend if it is couple of hundred £ or thousands....

This is all my view point.

Do you have a copy of that letter and are you still living in England?
If yes, then it's worth taking the letter to your local Citizens Advice Bureau for some free legal advice. It may be the case that they will not discuss it with you as it pertains to your sister. Definately worth a try though.