Pastor Housing Allowance -- Mid Year Resignation

My wife was a pastor with a housing allowance provided.  

 

she quit her job as a pastor in April.  Her W2 indicates a housing allowance of about $15000.   

What expenses from the year can be counted toward this $15000?  For example, the property tax bill was mailed after her resignation--it is not in escrow. 

 

Can I deduct the whole portion? the prorated portion based upon months emloyed? only the portion mailed while she was still employed?