I filed almost 21 business days ago, why has my refund not been approved and my tax return is still in review?

[CatinaT1]

Once your return is filed, TurboTax has no control over the processing of your return or the release of your refund.

Here are a couple FAQs to track your refund:
When will I get my federal tax refund?
How do I track my state refund?
Why does Where's My Refund say "approved" but TurboTax still says "accepted"?

[xmasbaby0]

TurboTax gets no information from the IRS after you file your tax return.  No one at TT knows that you are under review or why.  Only the IRS can tell you and only the IRS is in control.  If the IRS needs more information from you they will request it by sending you a letter.  You can watch the IRS refund site for information.