My understanding is:
Company can buy EV and get 100% first year writeoff (you will have to pay that back when you sell because it will be "profit", but if you then buy another (and the scheme still exists) that's moot. Tax rate might change for the worse though ...).
Benefit-in-Kind on EV is tiny (I have both EVs as Company Cars)
You could perhaps also consider Salary Sacrifice (but I expect that Company Car would be better for a company-owner)
Assuming you have, or get, an overnight Off Peak rate and charge overnight (i.e. off-street parking) then settling up with the business for the electricity cost should be OK, but you might need some way of monitoring it. The "isolation box" at my distribution board, which feeds the car charger, has a kWh meter on it. You can log what the car adds (e.g. using something like TeslaFi), but that won't catch every trip, and it is "received by car" which is not the same as "Delivered from the grid". Or you could pay for the "fuel" and get reimbursed from the company for "Business miles" - you might well be paying 5P a mile and getting 20-45P back ... no idea if its worth the candle though.
Your accountant definitely best person to check all that with.
If you charge at Supercharger you will get an Invoice (to the APP on your phone). I have a company credit card logged on MyTesla account, and my book keeper has the APP and downloads the invoices (but you could obviously do that yourself). I also have the £9.99-ish monthly connectivity pcakage, also on that Company Card (different route to get those invoices AFAICR <sigh>, but still a company expense).
I suggest you try
ABetterRoutePlanner and put in the CONFIG the vehicle(s) you are considering buying, and choose your averagely worst / fastest & longest journeys, and set weather to "Winter / Terrible" (worst case) and see what route it finds and what your arrive %age would be. Its data is pretty accurate, so likely to be realistic - it will also show you where you could charge, and how long it would take.
When I got my first EV, 2015, I was doing 35K miles a year. Far far fewer charging locations back then, and car had max real-world range of 240 miles, and I was out-of-range and charging 2x a month. The replacement will do 300 miles (real world motorway, "at a pinch") and my out-of-range journeys are now only a couple of times a year. Don't underestimate how much difference a bit more real-world range makes. 50 more miles, on top of any already nearly-enough-range, means you won't have to stop to charge on those borderline journeys, avoiding the time (5-10 minutes for leave-motorway-and-rejoin, plus charging time), plus risk of "chargers busy and have to wait". The first model I ordered was discontinued during my wait, and I was offered larger-or-smaller battery replacement. I paid up for the bigger one, a lot of extra money back then, and once I'd got over the £-pain! it was an excellent decision by reducing the number of journeys where I had to charge.
Stopping to charge means:
Some time stationary. If you do emails whilst charging, which you would only do when you got home, its completely time-neutral. If you are going 200+ miles you probably want a pee and a coffee anyway!
Chargers might be busy. I try to NEVER charge on the outbound journey, as it makes the arrival time unpredictable. On the return I don't care - I just do my time-neutral emails
Consider the reduced cost (and disruptive TIME) of servicing. Depending on what the Vendor requirements are for servicing once a year / 35K miles may be fine. You won't use the brakes hardly at all, so won't need new pads until 150K miles, and no cam belt / lengthy servicing tasks. I have a company service mine who is mobile (
Cleevely Motors), so they come to my home or office and service the car on the driveway - saves all the hassle of take-to-dealer. Last EV I didn't service at all for last 50K miles (Tesla took it in as part-ex without quibbling that), and new ones I service at around 30K interval - its a lot less inconvenience than service interval of ICE (i.e. for a high mileage driver)
I think from a financial point of view you may be able to save some money but with increasing cost of electrics this may even out.
Home charging with an off-peak rate of, say, 20p and 4 miles per kWh is 5P a mile. Range Rover type diesel is 20P a mile, and Eco-Box is 10P - and personally I wouldn't want to have to do 30K miles a year in an eco-box ...
... also 30K miles a year in an ICE is at least 8 hours a year standing-and-filling and queueing-to-pay. I look at those as billable hours
When I charge the EV on a trip I'm doing emails, not standing-pumping
