The math sounds trivial — add 90 days — but the date people announce to their new employer is wrong surprisingly often, usually by one day (does the notice clock start on the day you resign, or the day after?) or by a weekend (your computed date lands on a Sunday). Both are exactly the kind of error that turns into an awkward call with a joining team. Get the real date:
What actually shifts the date
The counting convention.Most Indian companies treat the resignation day itself as day one of notice; some start from the following day. It's one day on paper, but if your relieving letter and your new offer's joining date disagree by that day, you'll spend an afternoon fixing it. Leave during notice. Many policies extend the notice period by leave days taken during it — a week off can quietly move your last working day a week out. Early release. The date can also move the other way: if your replacement is ready or you negotiate a buyout of the remaining days, your effective date is whatever HR agrees to in writing. Whatever you compute here, the date in your acceptance-of-resignation email is the one that counts — it's also the date your full and final settlement clock starts from.
Working backwards from a joining date
The more useful direction, if you're planning a switch: take the joining date you want, subtract your notice period, and that's your resignation deadline. On a 90-day notice, an offer you want to join in January means resigning by early October — which is why a long notice period costs you well before you resign: your job search has to start a full quarter before you want to move, not when the perfect posting appears.
Directional, not contractual: company policy on counting, holidays, leave during notice, and early release varies — your employment agreement and HR's written confirmation are the source of truth for the actual date.