here is some information I found on the receipt number that has 900 what is USCIS computer workday 900? It is when one particular employee in the U.S. Citizenship and Immigration Services is required to work on a specific day of ithe year. The USCIS receipt number 900 was first implemented a long time ago as part of an effort by Congress to reduce government spending. This measure has been kept in place since then, and it is expected that it will continue for some time to come. It doesn’t affect all workers but only those who fall under certain categories such as I.T. personnel or other specialized roles where their services are critical for the smooth running of things at any given point in time. Overall, To notice 900 in this place does not mean a computer has worked for that long a period of time. Shared by users, this is an actual case number. For certain cases, there are exceptions to the rule.