@Milan Rao I don't believe it's possible to change the Tax period. Are you closing your Tax periods? If you're not then the system will assign Tax Period based on Transaction date so if I book a Bill today dated January and my tax period for January is still open that will be the Tax Period assigned even though the Posting period is June.

Yeah i figured that is the problem. is there a way you can modify the historical transactions in a way that you don't have to recreate the transactions. so that it post in right period. I closed the period and tried to change the date but it does not change the period. It seems like once you click save it gone for good.