You can request a Singapore citizenship confirmation letter in person at:
Registry of Citizens
Citizen Services Centre
10 Kallang Road, Level 6 (next to Lavender MRT station)
Operating hours are 8.00 am to 4.30 pm on Mondays to Fridays, and 8.00 am to 12.30 pm on Saturdays.
Longer-than-average waiting times are to be expected on the following peak times:
- Mondays, Fridays, Saturdays
- The day before or after a public holiday.