Do I have to pay tax

Hi built a new house in 2008, 2010 before finished. Our old house we did nit sell as reccession kicked in. value like all houses went to floor. I rented house for 4 months lying idle now ever since. I have not registered as landlord as not letting, did pay household charge. So as this is seen as buy to let do I need to pay any tax with nobody in house.... Also just lost job so will have toput on % or not pay or hipe I get job, main thing is do I owe any tax. If I sell it will only get 50% of amount owed... So can not see bank acceptdid happening that if it did happen....

You say you paid proeprty charge. I assume you do not mean NPPR which you should have paid in 2011 and 2012 -(and possibly for 2010 if builidng was completed and signed off before end March ).

Read NPPR.ie

Sorry to appear rude but your post is not too clear, especially last two lines.

Thankyou nick. Typed it on mobile and hard to go back over lines, will use ipad in future.

Also new house has not been signed as completed yet by our architect,.so then no charge would be due on old house yet, is that correct

If you have rental income of any sort, this must be declared. It is between you and the revenue as to whether you owe tax.( based on your other income etc) If you own a house thats not your principal private residence, then the nppr is due on this.
I would like to add, as oldnick said, your post us not clear. You should make sure your post is a clear a possible. This is typed on an touch, so it can be done!