After the tax return has been Accepted by the IRS (meaning only
that they received the return) it will be in the Processing mode until the tax
refund has been Approved and then an Issue Date will be available on the IRS
website.
See this IRS website for federal tax refund FAQ's - https://www.irs.gov/refunds/tax-season-refund-frequently-asked-questions
If over 21 days since being Accepted by the IRS and the tax
refund is still Processing you can call the IRS and speak with an IRS agent
concerning your tax refund.
Call the IRS: 1-800-829-1040 hours 7 AM - 7 PM local
time Monday-Friday
When calling the IRS do NOT choose the first
option re: "Refund", or it will send you to an automated phone
line.
So after first choosing your language, then do NOT choose
Option 1 (refund info). Choose option 2 for "personal income
tax" instead.