Before you start

Employer group medical cover, or a private policy
Vaccinations appropriate to India — typhoid and hepatitis A as a baseline
A hospital identified near home before you need one
Passport and address proof for hospital registration

Step-by-step

1
Read the group policy carefully
Check the sum insured, daily room-rent sub-limit, disease sub-limits, maternity terms, pre-existing waiting periods and dependant cover. Cover normally ends the day employment does.
Via employerWho: You and HRFirst month
2
Add a super top-up or an international policy
An Indian super top-up is cheap and raises a thin group ceiling substantially. An international policy costs more but travels with you and covers treatment outside India.
OnlineWho: You
3
Register at a large private hospital near you
Apollo Multispeciality at Canal Circular Road, AMRI, Fortis Anandapur, Woodlands and Belle Vue are the main options, with the government SSKM campus as the state's tertiary centre. Do one routine consultation so you exist in a system, and check the cashless network.
In personWho: YouWeek 1–2
4
Take dengue seriously from July through November
Kolkata records substantial dengue numbers every monsoon and the season extends well past the rain. The aedes mosquito breeds in clean standing water and bites during the day. Clear plant saucers and roof drains, use repellent, and get a platelet count for any sudden high fever rather than waiting.
In personWho: YouJuly–November
5
Plan for the winter air
From November to February Kolkata's air quality deteriorates sharply. An air purifier at home is a reasonable investment for anyone with asthma or young children, and checking the daily index becomes routine. Outdoor exercise is better in the afternoon than at dawn in those months.
Mobile appWho: YouNovember–February
6
Know the emergency drill in advance
112 nationally, 100 for police, 102 or 108 for an ambulance. For planned admissions at a network hospital ask for cashless pre-authorisation; off network you pay and reclaim, with notification usually required within twenty-four hours.
In personWho: You

Documents you’ll need

Insurance policy document and TPA cashless card
Passport and visa, required at admission
Vaccination records and a list of medications by generic name
Proof of Kolkata address

Things most newcomers don’t know

Kolkata's winter air, not its summer, is the measurable health risk.

From November to February, cool still air, low wind and regional biomass and vehicle emissions combine to push Kolkata's particulate levels to among the highest in India, second only to the Delhi belt. It coincides exactly with the months the weather is otherwise delightful and everyone wants to be outdoors. An air purifier at home and a habit of checking the index change the exposure materially, and dawn — when people instinctively exercise — is usually the worst hour of the day.

Source: Central Pollution Control Board

Dengue here has a long tail that runs past the rain.

Kolkata records large dengue numbers annually and the season extends from July into November, well after the monsoon ends, because the aedes mosquito breeds in small volumes of clean standing water rather than in floodwater. That means your own balcony, plant saucers, roof drain and air-conditioner tray are the relevant sites rather than the street. A sudden high fever warrants a same-day platelet count rather than a wait-and-see.

Source: National Center for Vector Borne Diseases Control

Room-rent sub-limits quietly shrink the whole Indian claim.

Many group policies cap the daily room rent they will meet, and taking a room above the cap lets the insurer proportionately reduce every other charge in the bill — surgeon's fees, tests, consumables. A policy you thought covered you leaves a large residual. Given how affordable Kolkata's private hospitals are, a modest policy with a clean room-rent clause beats a large one with a restrictive cap.

Source: IRDAI — policyholder information

Kolkata's medical tradition is deeper than its current reputation suggests.

The Calcutta Medical College, founded in 1835, was the first institution in Asia to teach Western medicine to local students, and the city retains an unusual density of teaching hospitals and specialists relative to its economy. The practical consequence for a resident is that specialist consultations are both available and cheap — you can see a senior consultant for a fraction of a Mumbai fee, often within days rather than weeks.

Source: community-reported