Paper checks are being phased out in an effort to cut costs.
About 93 percent of payments are now made electronically.
But about five millions checks are still mailed each month.
The Treasury Department says that mailing costs $4.6 million a month.
Those who fail to switch over will still get paper checks after March 1st.
A Treasury spokesman says they will contact those people in a quote -- "more personal, direct way" -- to ask them to switch.