Finally last month, Mr. Amy contacted the Taxpayer Advocate Service, an independent watchdog within the IRS, and a representative told him that his return was under review, and to keep waiting. The IRS says it delivers nine out of 10 tax refunds within 21 days, a time frame that hasn’t changed for e-filed returns in two decades. For taxpayers filing on paper, refunds can take four weeks or more, the IRS says.