In the recent entry on the Mills-McCartney divorce arrangements, I quoted this:

This is not a case where the principle of sharing of the “marital acquest” is engaged at all.

This term was new to me. It seems a good solution for Zugewinn in German law: the property acquired by both spouses from the date of marriage on, which may be divided fifty-fifty in Germany if so agreed or in default of a contract. The situation in England is different, but still it can be necessary to talk about this amount as one of the factors.

I find acquest in the OED:

3. Law. Property gained by purchase, or gift, or otherwise than by inheritance.

Used in this sense in French and in jurisprudence, it says in the etymology.

Google reveals 112 uses, and I think it must recently have been taken up. Probably it was one of the recent big cases where the concept needed to be discussed that used it and was widely reported.
Here‘s an example:

Increasingly on divorce (and the same principles are likely to apply on the dissolution of civil partnerships) the court is interested in ascertaining what has been described as the ‘marital acquest’, that is, the assets accumulated by the parties during their marriage.

I see it was quoted in Miller v. Miller.

This does not mean that, when exercising his discretion, a judge in this country must treat all property in the same way. The statute requires the court to have regard to all the circumstances of the case. One of the circumstances is that there is a real difference, a difference of source, between (1) property acquired during the marriage otherwise than by inheritance or gift, sometimes called the marital acquest but more usually the matrimonial property, and (2) other property.

Zugewinn is usually translated as accrued gains or surplus.