For the second quarter of 2019 (April 1 through June 30, 2019), the IRS interest rate on individual tax refunds and tax underpayments is remaining at 6% (Rev. Rul. 2019-5). This is the same rate that applied in the first quarter of 2019.
Keep in mind that if you are due a refund on your 2018 return, and you file by the April 15 due date, the IRS will not pay interest on a refund that it issues within 45 days; that is, by May 31. If you file after the April 15 due date, no interest is paid on a refund issued within 45 days of your filing date.
For corporations, the second quarter IRS interest rate on underpayments is generally 6% (same rate as for individuals), but for large corporate underpayments, the rate is 8%. The interest rate on a corporate overpayment is generally 5%, but on the portion of a corporate overpayment exceeding $10,000, the rate is limited to 3.5%.
Items directly reducing income. Personal deductions such as for mortgage interest, state and local taxes, and charitable contributions are allowed only if deductions are itemized on Schedule A, but deductions such as for alimony, capital losses, moving expenses to a new job location, business losses, student loan interest, and IRA and Keogh deductions are deducted from gross income even if itemized deductions are not claimed.