ALBANY — Nearly 900 state workers slated for Dec. 31 layoffs are getting more in the mail than season’s greetings — letters explaining their contractual right to bump someone else to the unemployment line in their place.

The 898 grim holiday mailings advise workers of their rights under union contracts and civil-service law concerning the layoffs, announced by Gov. Paterson last month.

Those who can bump less senior colleagues must decide within a given period.