Seniors and others who check their Social Security information online now are required to use "a text-enabled cell phone" to access their personal information.

The more than 26 million Social Security account holders were notified of this new rule, which took effect Monday, by email late last week. A detailed statement about the change was posted on the Social Security website on Saturday.

"Now, all new and current my Social Security account holders will need to provide a cell phone number able to receive text messages. People will not be able to access their personal my Social Security account if they do not have a cell phone or do not wish to provide the cell phone number," according to the announcement.