As with many things, averages are pretty worthless.

You mostly have two primary costs.

- Possible upgrades to living space so that you can "lend" your employer an office.

- Possible significant time/cost savings by not having to commute.

Mostly these aren't borne by the same people.

It's just anecdotal, but I found myself unintentionally saving money like crazy when I was WFH during lockdown due to not selling out every day for fuel, parking and buying lunch. But then again I'm someone who always pays the 'disorganisation tax'. I'm sure people with more optimised spending (e.g. catching the bus, bringing their lunch in from home etc.) didn't see as much of an effect.