Certificate also works, but I prefer affidavit. Another option is Letter of Employment

Daca persoana in cauza lucreaza in prezent in cadrul firmei respective atunci traducerea corecta ar fi "Employment verification letter" (US); daca contractul de munca a fost incheiat si se doreste o dovada a angajarii trecute atunci traducerea ar fi "certificate of employment".

"Certificate of employment" - Certificate issued by the employer when the employment relationship ends, supplied at the employee's request in accordance with the 2001 Contracts of Employment Act. The certificate of employment is important from the point of view of the employee's position in the labour market and social security benefits.
If the employee merely requests a straightforward certificate of employment, it is supplied in a brief form which in addition to the names of the parties, title, signature and date states only the duration of the employment relationship and the nature of the work performed. If the employee requests that the certificate should additionally include the reason for the termination of the employment or an assessment of the ability, diligence and conduct exhibited by the employee, the certificate supplied must also give this information. The presumption as regards this assessment is that it represents a testimonial supplied by the employer reflecting that employer's personal judgement. The right to be issued with a certificate of employment normally expires after 10 years. An employer who fails to comply with the provisions regarding certificates of employment incurs liability to pay a fine and compensation for any damage thereby caused.