Firstly: 

It is not permissible to put money in riba-based banks unless that is essential in order to protect it, so long as that is without interest. See the answers to questions no. 23346, 22392 and 49677. 

Secondly: 

If one full year has passed since you acquired the nisaab (minimum threshold) then zakaah must be paid immediately, and it is not permissible to delay it beyond that when one is able to pay. A person does not have the choice of selecting a particular month for paying zakaah on his wealth, rather that month should be after one year has passed, unless he is paying it in advance in Ramadaan, before the year has passed, in which case there is nothing wrong with it. But after the year has passed, it is not permissible to delay it until Ramadaan. 

See the answer to question no. 26716 and 8400. 

Thirdly: 

If you pay zakaah on all your wealth, even your monthly salary, this is safer and is the easiest way of paying zakaah on what you have saved of your salary. 

See the answer to question no. 26113 and 50801. 

Fourthly: 

We have already explained that riba (usury) is haraam, and it is haraam with regard to building and buying houses. If that loan is riba-based, then you must hasten to repent and get rid of it, seeking that which is with Allaah and fearing His punishment. 

See the answer to question no. 45951, 21914, 22905 

Fifthly: 

With regard to the zakaah of one who is in debt, the correct scholarly view is that the debt cannot be subtracted from the wealth on which zakaah is due. In the example which you mention, you have to pay zakaah on the full one hundred thousand, and you cannot subtract from it the debt that you owe. 

See the answer to question no. 65763, 22449 and 22426. 

And Allaah knows best.