It
could be due to an offset or a change to your tax return by the IRS:
An
offset is used to pay off past-due federal tax, state income tax, state
unemployment compensation debts, child support, spousal support, or other
federal non tax debts, such as student loans. Also, you could see a change
in your refund amount because the IRS made a change to your tax return.
Here
is more information:
https://ttlc.intuit.com/replies/3288510