# Registering for a Singapore Unique Entity Number (UEN)
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In order to start a registration with the SSIR you must first obtain a Singapore Unique Entity Number (UEN). A UEN is a unique entity number you receive when you register your business with the Account and Corporate Registry Authority (ACRA), for more information see [Who Must Register with ACRA?](https://www.acra.gov.sg/how-to-guides/before-you-start/who-must-register). The amount of time to process can vary depending on how easily the ACRA can validate your request.