Zakah should at least be equal to 2.5% of a person's savings in a year. I want to know if Zakah for a given year is to be paid during Ramadan or if it can be paid anytime during the year?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The Zakah for money (wealth) or tradable merchandise which reach the minimum amount liable for Zakah, has to be paid at the end of a whole lunar year period any time during the year.  It is not permissible to delay it until Ramadan because it has to be paid as soon as it becomes due.

However, if someone wants to advance it and pay it during the month of Ramadan before a whole year passes on it, so that his year will start from Ramadan, then there is no objection to that.  But if there is an increase of wealth after having paid the Zakah and before the starting of the year, then he must pay the Zakah, and it is not permissible to delay it, in this case, to Ramadan of the next year because the period of a year is when a full year passes from the time it had begun in principle.