But you arent receiving any interest on it and do not have access to it, if you think you will spend it if it goes into your savings account then set up an allotment for it to go into a mutual fund or IRA so you never see it or miss it.
Think of it this way, would you rather keep more of your income or pay it to the government?
If you adjust your witholding so that you break even at the end of the year then take the extra ammount you recieve each month and invest it (any number of ways) into an avenue that will pay you that interest instead of the government wouldnt this benifit you more than 1 lower lump sum at the end of the year.
For example say you get a return of $1200 at the end of the year, this means that the interest on that ammount has gone to Uncle sam. Now wouldnt you rather recieve an additional $100 each month + interest, and as you put in more your interest will compound.
Your money, your choice.