The split between ICP and GDRFA is one of the most commonly confusing aspects of UAE visa administration, even for long-term residents — and the rule for which one applies to you comes down to a single factor: which emirate originally issued your residence visa.
The one rule that decides it
If your residence visa was issued in Dubai, you use GDRFA — its portal, app, or an Amer Centre in person. If your visa was issued in any other emirate (Abu Dhabi, Sharjah, Ajman, Ras Al Khaimah, Fujairah or Umm Al Quwain), you use ICP Smart Services, the federal system covered in this site's dedicated ICP guide. The two systems do not cross-process each other's files, so check the issuing emirate shown on your current visa before choosing a portal.
Why this confuses even experienced residents
Someone who moved emirates, changed jobs, or simply hasn't needed to renew in a few years can easily lose track of which system currently applies to their file, especially since both systems handle broadly similar transactions (medical test, Emirates ID, fee payment) using different portals and sometimes different terminology for the same underlying step.
What to do if you are not sure
Check the issuing emirate printed or shown digitally on your current residence visa or Emirates ID record — that single detail tells you definitively whether GDRFA or ICP Smart Services is your correct channel, rather than guessing based on where you currently live or work.