Online through the IRS Get Transcript tool at IRS.gov
By mail using Form 4506-T, Request for Transcript of Tax Return
By phone at 800-908-9946
In person at an IRS Taxpayer Assistance Center with an appointment
Through a tax professional or authorized third party with proper authorization
For business transcripts, use the IRS business transcript request options on IRS.gov or Form 4506-T
For wage and income transcripts, request the Wage and Income Transcript through the IRS transcript services
For account transcripts, request the Account Transcript through the IRS transcript services