Sometimes. So Dec is the worst case, especially if you have a longish period. You end up paying top rates on this year, then suddenly have no income come January.

Of course details vary country to country.

One fairly common thing is you can opt to take it as an lump sum now, or take it as a monthly salary - but with the proviso that if you take a new job you stop getting it. This is often the way benefit extensions work also. Sometimes the monthly option is larger.

So financially you are often better off with the lump sum, but it can be a tax hit.

Yes. Or at least here in Ireland

If this was in Ireland, the workers wouldn't be laid off as of today - they'd at least have the option of a "consultation period". While that might be just a formality in terms of retaining their jobs, it would give anyone who wanted the option to get their severance payment in January instead.