It most certainly is a requirement of the British Standard. Extinguisher maintenance companies need to provide a written report and a certificate of inspection. (These can be combined to form one document.)
9.4.1.1 Provision of a written report
The competent person should advise the responsible person in a written report:
a) of any extinguishers that have been condemned, not maintained and/or are missing;
b) of any permanent replacement extinguishers required to replace those extinguishers reported in a);
c) of any additional extinguishers required to ensure that the level of cover at the premises is at least sufficient and, where applicable, in accordance with BS 5306-8;
d) that any replacement or additional extinguishers reported in b) or c) should be provided as soon as possible; and
e) of the responsible person’s obligation under fire legislation to provide an appropriate level of fire-fighting equipment at all times.
9.4.1.2 Maintenance documentation
A certificate of inspection should be issued in all cases.
The certificate of inspection should include the following information:
a) the name, postal address and telephone number of the maintenance company;
b) the date of maintenance;
c) identification of the maintenance technician;
d) a list of all portable extinguishers included in the maintenance programme, including all non‑conforming equipment, and recommendations for appropriate corrective action or reference to where this information can be found;
e) the signature of the responsible person, which should be obtained upon completion of the service visit and prior to the service technician leaving the premises, or a record of the reason why this is not possible (e.g. unmanned sites);
f) a statement that, apart from non‑conforming extinguishers as recorded, all portable fire extinguishers have been inspected and serviced in accordance with this standard, i.e. BS 5306‑3.