Funds maintenance for Tier-1 (General) dependent extension

Hi,
Tier-1 (General) dependent has been in the United Kingdom for more than 12 months.

how much do we need to maintain the funds in the bank account for Tier-1 (General) dependent extension application and how long for ?
is it £630 for 90 consecutive days? please correct me if i am wrong

FYI-
Tier-1 (General) main applicant is now a British citizen.

thanks in advance.

https://www.gov.uk/tier-1-general/family-members

If you’ve been in the UK for more than 12 months, you must have £630 for each dependant.

You must have proof you have the money, and that it’s been in your bank account or your dependant’s bank account for at least 90 days before you or they apply.