Once you pay salaries above the basic exemption, you must deduct tax at source under Section 192 based on each employee's estimated annual income and chosen tax regime, deposit it by the 7th of the following month, file quarterly returns in Form 24Q, and issue Form 16 annually.
Common startup slip-ups: forgetting TDS on the founders' own salaries, missing TDS on contractor payments (Section 194J/194C — different sections, different rates), and depositing on time but filing returns late, which triggers per-day fees under Section 234E.
TDS is unforgiving of casualness because every rupee is traceable. Put it on an automated calendar from the first hire.