A SSDI claimant's last day of significant work is the date of onset for disability (and includes unsuccessful work attempts). Claimants are required to wait 5 months from the onset date before eligibility for benefits begins. SSA's receipt of a written statement by a claimant expressing an intent to file for SSDI triggers a protective filing date, as long as an SSDI application is completed within 6 months. An SSDI claimant can receive retroactive benefits for up to 1 year prior to the protective filing date, if both disabled and eligible during that period.