Is 42000 DKK Per Month sufficient to live ?

Example: Yearly income 510,000 kroner, living in the municipality of Gladsaxe, married, spouse doesn't work = tax 167.801,10 kroner. (If your wife has a job of her own, your tax will amount to 184.292,10 kroner).

You shall not expect to find a cheap housing. Only new housings are available if you haven't been signed up for years or know an administrator. Therefore expect to pay 144,000 kroner + utilities 25,000 kroner for a housing. Household another 60,000 kroner. Commuting expenses depend on the distance, but expect 12,000 kroner.

When you consider whether this pay is enough or not, don't expect your wife to have an income. It isn't easy to find a job when you don't speak Danish, even if you are highly skilled. The jobs on the positive list (https://www.nyidanmark.dk/en-GB) gives an indication of her chances.

https://www.prosa.dk/?id=6745
Prosa is the union of IT professionals. You'll find a guideline for the pay level within IT on their site.

I take that you are also offered a pension scheme. Not under 10 %. You won't have the saved amount at disposal before you retire, and therefore the amount isn't taxable before that time, but when the time comes, the pension is taxated exactly as the salary was.  However, many expats have left Denmark long before their retirement, why they can choose between having the pension paid as part of the pay, and they have full access to the amount.

When you look at the pay guideline, the amounts are exclusive the pension scheme.

/Nellie