Agency or contract worker unpaid

What usually matters in this situation, and the papers to keep ready before you meet an advocate or free legal aid (call 15100).

Your situation

Attendance, timesheets, rosters, work emails or work-group messages
Shows work was done for the months claimed. Where: Work email, WhatsApp work groups, attendance app.
Employer's registered name and address (and GST/CIN if known)
Needed for any notice or complaint. Where: Offer letter, salary slip, invoices, GST portal search, MCA company search.
Details of the contractor/agency and the principal company where you worked
Both may have obligations to pay. Where: Gate pass, agency letters.

Appointment letter, offer email or contract — States the salary and terms.
Salary slips — Shows the agreed salary and any PF/tax deducted.
Bank statement showing past salary credits from the employer — Shows the employment and the usual amount.
EPFO (UAN) passbook or ESI records — Employer contributions are independent proof of employment.
Employee ID card, visiting card or uniform — Supporting proof of employment.
Records of cash wages (notebook entries, messages, co-workers' names) — Cash wages need indirect proof.
Anything linking you to the employer (photos at work, delivery records, customer messages, co-workers) — Without formal papers, several small pieces of proof can work together.
Your written request for salary and the employer's replies — Shows the employer knew and did not pay.
Resignation, termination letter or relieving letter — Final settlement dues depend on the exit date.

Forums and rules depend on whether you are an "employee" or "worker", the type of employer and the state. Your advocate will check.

General information, not legal advice.