I researched this for you and found that if your refund was less than you expected, it may have been reduced by the IRS or a Financial Management Service (FMS) to pay past-due child support, federal agency nontax debts, state income tax obligations, or unemployment compensation debts owed to a state. If none of these apply, then just know that the Federal Government has been very busy sending out refunds as well as stimulus checks. This could be the reason you have not been able to get through to them by phone. If you have not yet, you should receive a letter explaining the difference, you can respond to that letter if the explanation is not satisfactory.
