With respect to the IRS rules...........I do not know what the FSA rules are.........

Every person filing a US income tax return is required to pay his taxes AS HE EARNS the money.

IRS and Congress were smart enough to know that no one can realistically do that--------too much bookkeeping involved.

So.........exceptions were established-------ie safe harbors--------if the safe harbors are followed, then penalties for underpaying during the year are NOT imposed.

The usual exception.........ie I would bet the most generally used...........is if a person pays in an amount during the year which is equal or greater than his tax liability for the PRIOR year, then the current year's tax liability can be ten million dollars, and he is not required to pay the difference.........ie the "estimated" amount and the actual computed amount for that current tax year...........until April 15, of that next calendar year, ie the typical filing date.

This applies to farmers, policemen, everyone.

So..........if your taxes for 2008 were 3000.........and you had paid in 4000 so that there was a 1000 refund..............your target amount is 3000 for estimated taxes for 2009 to be paid during 2009.

The payment of the 3000 can be by withholding if you or your wife works at a non-farm job, or if you work for your corporation and receive a salary.  In fact, that is what we usually due for guys who get a salary (or their wives)-------juggle the amount of the oncoming year's withholding to equal at least the prior year's tax, so that they do not have to file their return before April 15.

If you are a farmer or a fisherman-----------and that is defined by determining if your GROSS income from farming (or fishing) is at least 2/3 of of your ENTIRE GROSS income inside the return.    So........take the GROSS receipts on the Schedule F, add the sales prices of any farm assets sold on 4797 or Sch D..............and compare that to the total gross receipts of the return..............most likely you will qualify as farmer.

And.......that allows you to file as a farmer for the ONCOMING tax year also............

But remember..........filing as a farmer only allows you special consideration with respect to avoiding the penalty for underpaying estimated income taxes.

If a farmer, then have two options to avoid the estimated tax penalty-----------pay ALL of the 2009 taxes by Jan 15..........and then file the return under the usual rules, ie April 15.

OR...............pay all of the taxes for 2009 by March 1, 2010.....AND file the return by that same March 1.

We only have one farmer who files March 1 (and of course pays then) any more...........pain in the tail to scramble to get things done by March 1, when we have so many corps due March 15.

These are really basic rules..........and have not changed for eons........so if you're dealing with someone from IRS who does not know them------------be alert, 'cause they could be deficient in other areas also.