It comes all at once. Your refund could have been adjusted if you owed back taxes or partial back federal taxes, had a judgment(s) against you (to include child support if it applies) or a lien. If so the amount owed would have been deducted from your refund to settle the amount due. The IRS while it was reviewing your return might have found error(s) that had to be fixed and once that was done it adjusted your amount. You can request your tax transcript directly from the IRS either online or in the mail and it will show you everything involved with in your return.
