The actual rules & regulations are determined by the Federal Public Service Commission of Pakistan
However, these rules regarding age of a candidate are in accordance with the previous rules of FPSC.

Cut-Off Date in terms of age, qualifications, domicile, etc. is 31 December, of the year prior to the year of examonation (if otherwise not changed by FPSC).

AGE-LIMITS for the CSS Exam of 2023 
Minimum Age on 31 December, 2022 : 21 years
Maximum Age on 31 December, 2022: 30 years 

The FINAL AUTHORITY for date of birth rests with the Federal Public Service Commission of Pakistan. 

IS RELAXATION IN AGE POSSIBLE?
YES, only in the upper age limit. Not more than 32 years of age in any case
2 years for persons who have 2 years continuous government service till the cut off date for the calculation of age
2 Years for the citizens of Kashmir
2 years for the candidates of certain districts of KPK
2 years for certain recognized tribe of Balochistan
2 years for the people from scheduled castes and Budhist community
2 years for candidates who are doing government job for two continuous years

DETAILED GUIDELINES FOR AGE RELAXATION
The upper age limit will be relaxed by two years up to the age of 32 years in respect of :—

(a) the candidates belonging to the Scheduled Caste and Buddhist Community subject to production of a certificate (Annex-A of Application Form) to be issued by Political Agent/DCO/ District Magistrate in support of their claim.

(b) the candidates belonging to the recognized Tribes who are permanent residents of the areas mentionedbelow and whose families have been living in these areas. Such candidates must attach a certificate (Annex- B of Application Form) to be issued by Political Agent/DCO/District Magistrate in support of their claim :—  

1. Balochistan.
2. Tribal Areas of D.I.Khan and Peshawar Divisions (including former Frontier States of Dir, Swat,Chitral and Amb).
3. Former excluded (Baluch) area forming part of the Dera Ghazi Khan and Rajanpur Districts.
4. Former Tribal Areas of Mardan and Hazara Divisions.
5. Upper Tanawal Area of Hazara Division.

(c) the candidates who are permanent residents of Azad Kashmir Territory, subject to submission of a certificate (Annex-C of Application Form) to be issued by Kashmir Affairs Division, Government of Pakistan.

(d) the candidates who are permanent residents of Northern Areas including Gilgit, Diamir, Baltistan, Ghizar and Ghanche, subject to submission of a certificate (Annex-B of Application Form) to be issued by the Political Agent/DCO/ District Magistrate.

(e) the candidates who are disabled namely, physically impaired, hearing/speech impaired (deaf & dumb) and visually impaired (blind), subject to submission of certificate of disability issued by the competent authority designated for the purpose by the Federal/Provincial Government.

(f) In Service Government Servants, Armed Forces Personnel, Contract employees, including the Government servants of AJ&K, who possess a minimum of two years continuous Government  service as on first January,  submission of Departmental Permission Certificate of the competent authority is a must. Employees of Nationalised Banks, State Bank of Pakistan,WAPDA, Regulatory Authorities, Autonomous bodies and other semi autonomous bodies are not entitled to age relaxation.

DATE OF BIRTH
 The date of birth accepted by the Commission is that entered in the following documents:

(a) Matriculation Certificate;
(b) Secondary or Higher Secondary School Leaving Certificate; 
(c) Certificate of birth from the Principal/Headmaster of the School from where a candidate has passed
his/her GEC, ‘O’ level or equivalent examination, showing the date of birth in the School Admission Register;
(d) In case of Christian candidates, Baptismal or birth registration certificate.

The FINAL AUTHORITY for date of birth rests with the Federal Public Service Commission of Pakistan.