I didn't receive my full federal refund

• One possibility is that you used the Refund Processing Service to pay your TurboTax Online fees. If you did, your TurboTax fee plus the additional processing fee is deducted from your federal tax refund.
• Another possibility is that your refund was reduced by the government, either to correct a calculation error or through a refund offset. You’ll get an explanatory letter from the government if your refund differs from what was on your filed return.

https://ttlc.intuit.com/replies/3301372

https://ttlc.intuit.com/replies/4143297

• Also, see question 14 from the IRS FAQs

https://www.irs.gov/Refunds/Tax-Season-Refund-Frequently-Asked-Questions

Q14: Why is my refund different than the amount reflected on the tax return I filed?

If you owe past-due federal tax, state income tax, state unemployment compensation debts, child support, spousal support, or certain federal nontax debts, such as student loans, all or part of your refund may be used (offset) to pay the past-due amount. Offsets for federal taxes are made by the IRS. All other offsets are made by the Treasury Department's Bureau of Fiscal Services (BFS). For federal tax offsets, you will receive a notice from the IRS. For all other offsets, you will receive a notice from BFS. To find out if you may have an offset or if you have any questions about it, contact the agency to which you owe the debt. See Tax Topic 203 for more information about refund offsets.

Another reason your refund amount may be different is if we made changes to your tax return that changed your refund amount. In this case you will get a notice in the mail from us explaining the changes. These reasons will be reflected in Where’s My Refund if they apply to your refund..