Here are the official rules by the WTF (World Tae Kwon Do Federation), regarding Poom and Dan certification.

Students under the age of 15 years old will receive what is called a “Poom Certificate” when they achieve 1st Degree Black Belt. Students above the age of 15 years old will receive a “Dan Certificate” when they achieve 1st Degree Black Belt.

Here is how it works: (see chart below)

Under 15 years old: A student can achieve 1st Poom, then 2nd Poom, then 3rd Poom under the age of 15 years old. Then, when the child/student turns 15 years old, they can simply convert the Poom to the equal rank “Dan Certificate”. There may be a small fee to do so – please check with your location’s director.

So for example, a 12 year old, 2nd Poom, Black Belt will be a 2nd Degree (Dan) Black Belt when he or she turns 15 years old.

If a child achieves 4th Poom Black Belt, then that student will need to wait till they turn 18 years old to convert that 4th Poom to a 4th Degree (Dan) Certificate.

Note that the WTF may award Dans outside these rules in exceptional situations, for example rewarding national champions in Olympic TKD Sparring.

Poom/Dan Minimum Time Required for Promotion Age Limits(Start from Dan) Age Limits(Start from Poom)
1st Poom N/a N/a Less than 15 years old
1st-2nd Poom 1 year N/a Less than 15 years old
2nd-3rd Poom 2 years N/a Less than 15 years old
3rd-4th Poom 3 years N/a Less than 18 years old
1st Dan N/a 15 years and above N/a
1st-2nd Dan 1 year 16 years and above 15 years and above
2nd-3rd Dan 2 years 18  years and above 15 years and above
3rd-4th Dan 3 years 21  years and above 18 years and above
4th-5th Dan 4 years 25  years and above 22 years and above
5th-6th Dan 5 years 30  years and above 30  years and above
6th-7th Dan 6 years 36  years and above 36  years and above
7th-8th Dan 8 years 44  years and above 44  years and above
8th-9th Dan 9 years 53 years and above 53 years and above