When I filed my taxes earlier this year, I was surprised to be owing the IRS over $10,000.


  • I did exercise a bunch of ISOs without holding them, and
  • apparently my request to change my withholdings from 1 to 0 was lost in transit or ignored by HR (I see my signed W4 from November 2017 in my employee documents vault); I was still on 1 withholding when I knew I should be on 0.

Still, it seemed $10,000+ was excessive, but I also read there were changes to tax laws that surprised many Americans, so I filed.

Since then, I've heard 2 coworkers say TurboTax said they owed $10,000, but a CPA brought that down to $2,000.

Is it too late or unadvised to go to a CPA now? Will any CPA take this kind of work in May? Will I be able to get a refund if there is a correction to be made?

  • 1
    One thing to note is that when you exercise and immediately sell ISOs, the income is almost always "reported twice" -- the spread between the price you paid to exercise and the market value of the stock at the time of exercise is both reported as wages on your W-2 and as stock gain on your 1099-B (because the "basis" on the 1099-B lists the price you paid, not the correct basis which is the market value of the stock at the time you exercised, since it was already counted in income). In this case, you would have to do an adjustment of the basis on your 8949, or you would be paying double taxes.
    – user102008
    May 9, 2019 at 5:09

1 Answer 1


To claim a refund, you typically have up to three years from the time you filed your original return, or within two years from the date you paid the tax — whichever is later — to go back and amend it.


It quite likely is easier to find a tax professional in May, since their peak season is March and April. However, you should consider just why you expect your tax to go down. If you can, get details from your coworkers about why their tax went down, and see whether it applies to you. CPAs can't just wave a magic wand make your tax bill go down; there has to be some reason for the decrease.

Also, you can end up ending a penalty if your final tax liability is significantly higher than your withholding, and your employer isn't going to be taking ISO exercise into account when calculating your withholding. So any time you exercise ISOs, or do anything else that will significantly increase your income above your normal paycheck, you should look into whether you need to make estimated payments.

So: you can get a CPA after April 15, but it's better to talk to one before April 15, and even better to talk to one before you exercise your ISOs.

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