43 CFR 2.50 - When will the bureau require advance payment?
(a) The bureau will require advance payment before starting further work when it finds the estimated fee is over $250 and:
(1) Demonstrate you paid prior fee within 30 calendar days of the date of billing; or
(2) Pay any unpaid amount of the previous fee, plus any applicable interest penalties (see § 2.53 of this subpart), and pay in advance the estimated fee for the new request.
(e) If the bureau requires advance payment, it will start further work only after receiving the advance payment. It will also notify you that it will not be able to comply with your FOIA request unless you provide the advance payment. Unless you pay the advance payment within 20 workdays after the date of the bureau's fee letter, the bureau will presume that you are no longer interested and will close the file on the request.