Before you start

Missouri residency and a Missouri address
A paid personal property tax receipt or a Certificate of Non-Assessment from the assessor
A Gateway VIP emissions certificate, for the city and the three affected counties
Proof of Missouri liability insurance

Step-by-step

1
Get the Certificate of Non-Assessment first
A new resident who was not liable for Missouri personal property tax in the previous year applies to the assessor for a Certificate of Non-Assessment — a tax waiver — which is free. Without it, or a paid receipt, the licence office will refuse to issue plates. If you live in the City of St. Louis, this is the City Assessor at City Hall; if you live in the county, it is the county assessor.
In personWho: YouWeek 1
2
Book the emissions test if your address needs one
The Gateway Vehicle Inspection Program covers the City of St. Louis and St. Louis, St. Charles and Jefferson counties. Petrol vehicles from model year 1996 and diesels from 1997, up to 8,500 lb, are tested biennially and on title transfer. A safety inspection is a separate thing and is not required in a vehicle's first ten model years or 150,000 miles.
In personWho: You
3
Take the driving tests unless you hold a valid US state licence
Missouri lets holders of a valid licence from another US state convert with vision and road-sign screening. A foreign licence is not a state licence, so plan on the written test, the road-sign test, the vision test and the driving test. Confirm the current position with the Department of Revenue before booking anything.
In personWho: You
4
Register the vehicle within 30 days
Bring the title or out-of-state registration, proof of Missouri insurance, the emissions certificate, the safety inspection if required, and the tax receipt or waiver. Missouri also charges state and local sales tax on a vehicle brought in from out of state at the time of titling, which is a substantial one-off bill people do not expect.
In personWho: YouWithin 30 days
5
Budget for the annual personal property tax from then on
Every year after that, the assessor values your vehicles at 33⅓% of true value as of 1 January and the collector bills you in the autumn, due 31 December. You need that year's paid receipt to renew the plates, so a missed bill compounds into an unregisterable car.
OnlineWho: YouAnnually, by 31 December
6
Learn winter and severe-weather driving here
St. Louis gets ice storms rather than reliable snow, which is worse for driving — freezing rain glazes the bridges over the Mississippi and the Missouri first. Spring brings severe thunderstorms and occasional tornadoes; flash flooding on the low river roads is routine.
OnlineWho: You

Documents you’ll need

Foreign driver licence, with certified English translation if needed
Passport, visa and I-94
Certificate of Non-Assessment or paid personal property tax receipt
Gateway VIP emissions certificate, where required
Proof of Missouri liability insurance and the vehicle title

Things most newcomers don’t know

No tax receipt, no plates — and a new resident has neither.

Missouri licence offices require the previous year's paid personal property tax receipt before renewing or issuing plates. A newcomer has never been assessed, so they need a Certificate of Non-Assessment instead, which is a different office in a different building and is free. It is the single most common reason a new arrival gets turned away at the counter.

Source: City of St. Louis Assessor — tax waiver

Which assessor you go to depends on the city-county line, not the address's look.

The City of St. Louis is an independent city with its own assessor at City Hall. A resident of Maplewood or University City — visually indistinguishable inner suburbs — goes to the St. Louis County assessor instead. Going to the wrong one costs a day.

Source: City of St. Louis Assessor — tax waiver

Emissions testing exists here and in almost nowhere else in Missouri.

The Gateway Vehicle Inspection Program covers only the St. Louis city and three-county area. Someone moving from Kansas City or from most of the state has never encountered it, and registration is refused without a current certificate.

Source: Gateway Vehicle Inspection Program

Bringing a car into Missouri triggers sales tax at titling.

Missouri charges state and local sales tax on a vehicle titled here from out of state, based on the purchase price, at the moment of titling — with a credit only in limited circumstances. On a recent car that is a four-figure bill arriving in your first month, and it surprises people who assumed they had already paid tax on it elsewhere.

Source: Missouri Department of Revenue

Common mistakes to avoid

Turning up for plates without a paid tax receipt or a Certificate of Non-Assessment.
Going to the St. Louis County assessor when you live in the independent city, or the reverse.
Forgetting the Gateway VIP emissions test and being refused registration.
Budgeting for registration without the sales tax charged when titling an imported vehicle.
Assuming a foreign licence converts on vision screening alone, as an out-of-state one does.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.