Imagine it is the autumn of 2018. You want to refer to something that will happen in 2019. Do you say it will happen A, “next year,” or B, “in the new year”? I contend that it you are British, the answer is likely to be B, and if American, A. My sense is that I encountered the whole “in the new year” thing for the first time while reading British novels and the British press and watching British TV.
It’s a bit hard to quantify my contention using many of my go-to databases and other tools, because Americans do say “ring in the new year” and similar expressions. However, Google Ngram Viewer allows for case-sensitive searches, so I searched for “In the new year” — the capital “I” ensuring that the phrase wouldn’t be preceded by “ringing,” “seeing,” “welcoming,” “bringing” or any such verb. Here’s what I got:
That is, it appears that in the twentieth century, “in the new year” as a standalone phrase was consistently more than twice as popular in the Britain than in the United States. And note that I’m not saying it wasn’t used at all here; it was just used less often.
The Corpus of Global Web-Based English, which offers a snapshot of nearly 2 billion words of text in 2012-2013, doesn’t allow me to separate out the “ringing-in-the-new year”-type usages (or at least I don’t know how to), but even so, it shows “in the new year” as being generally much more common in Australia, Canada, Britain, and (especially) Ireland than in the United States.
Here are just a few of the 1,153 times the phrase was used in British web pages:
And here are some of the 236 American hits:
Numbers 1, 2, and 8 are of the “welcome-in” form, but the rest have a definite British “in the new year feel.” Enough, at least, for me to designate the phrase On the Radar.
notoneoffbritishisms.com 
Here’s another example (I think): “in hospital”. I heard this phrasing a lot when I worked for a magazine mastheaded by British, Australian, and South African editors. Now I hear Americans using the phrase. I always mentally insert “the.”
Libby, in all my years of doing this, I’ve only come across one American “in hospital”–please send along any you find!
To this Brit, “In the new year” would only be used in December, suggesting whatever is being discussed will happen pretty quickly after the Christmas/New Year holiday period. In all other cases, it’s “next year”.
A general rule of thumb (not that it’s ever really written down) would be if the date discussed falls into that period when you find yourself saying “Happy new year” to people when you meet them – like when you return to work. So generally the first week in January.
Any fellow Brits agree ?
Yes, I think I do. If I’d been discussing my summer holiday with family during Christmas, I’d probably says “Next year I’m going to….”. But if I needed to replace some item which had just broken and would be doing it in January, I’d say “I’ll do that in the new year.”
I agree, though I’d say it goes up to about the first week or two of February – February half term, say, or Pancake Day.
I agree. We often use a qualified phrase such as ‘early in the new year’.
In my experience, in Australia, the usage is that ‘In the new year’ implies an event in the first weeks or months of the new year, and the phrase is only used at the end of the year. ‘Next year’ is more general, less specific and favoured by procrastinators and gunners.
I agree – in Australia, I’d expect that ‘in the new year’ means roughly ‘early next year’; the first would be said coming up to Christmas, for something that would happen after the Christmas/New Year break, possibly after school goes back at the end of January; it has a sense of a fresh start. Early next year could be said at any time.
Agreed. Another usage I’ve heard has overtones of “You’re asking for {item) this close to Christmas? You’re going to have to wait” implied. I wonder if this implication is more an Australian/NZ thing, since we have much more of a break at Christmas than the northern hemisphere? Schools even more so, but even businesses sometimes don’t come back from Christmas break until a couple of weeks into January.
Agree with the Australian and British responses here. “In the new year” would refer to the first weeks or months.
“We’ll start rolling out the revised training schedule in the new year” would definitely not refer to any point in the twelve months between January and December but to January or, at a push, February.