The IRS believes most issues have been resolved. It urged those who had been unable to register to try again, but to avoid peak hours from 1 p.m. to 4 p.m. EST daily.
For those registering for the first time, the system will be unavailable from 3:30 p.m. Saturday until 8 a.m. Tuesday for maintenance.
An unexpectedly large number of Preparer Tax Identification Number renewals attempted last week swamped computer systems at the Internal Revenue Service. The result was slow performance, timeouts and an inability of those trying to renew their numbers to do so.