what does your lease say?
Contrary to popular belief, when you sign a 1 year lease, the entire amount of rent becomes owed. You do not incur a debt each month equal to 1/12 of the total. Monthly payments are included for the convenience of the tenant. If your lease says the entire amount due for the term written is $XXXXXX and the monthly payments listed add up to that, then there is no basis for the rent to be pro rated for May of 2015.

