IRS Direct Pay (Make a Payment) https://www.irs.gov/payments/direct-pay
Where’s My Refund (IRS Refund Tracker)https://www.irs.gov/refunds
IRS Get Transcript Online https://www.irs.gov/individuals/get-transcript
IRS Tax Withholding Estimator (Official Federal Calculator)https://www.irs.gov/individuals/tax-withholding-estimator
IRS Verify 501(c)(3) status, eligibility to receive tax-deductible donations https://www.irs.gov/charities-non-profits/tax-exempt-organization-search