happy new year
/ˌhæpi njuː ˈjɪər/
"Happy new year" is the universal English greeting exchanged around the turn of the year, from New Year's Eve through the first days of January. Its German counterparts vary slightly depending on context and regional tradition.
1. Frohes neues Jahr!
The most universal and stylistically neutral translation, equally at home in written messages and spoken greetings.
2. Gutes neues Jahr!
Equally widespread and fully interchangeable with 'Frohes neues Jahr'; feels somewhat more casual and is especially common in spoken language.
3. Prosit Neujahr! [informal] · regional, festive toast
Predominantly Southern German and Austrian; used specifically as a toast when clinking glasses at midnight. Not a general-purpose greeting for cards or messages.
Notes
On greeting cards you often see 'Frohes Neues Jahr' with a capital N. Grammatically it is an exception (attributive adjectives stay lowercase in German), but it is widely accepted as a festive stylistic convention. 'Prosit Neujahr' is not a full substitute for the everyday greeting; it belongs specifically to the act of toasting and carries a distinctly Bavarian and Austrian flavour.