The Maryland Department of Assessment and Taxation said that application forms for the 1980 Homeowners' Tax Credit Program and the new 1980 Renters' Tax Credit Program and booklets explaining both are available at all public libraries and assessment offices. The tax credit program provides tax credits of up to $900 a year for homeowners, based on a comparison of their income to the actual property tax bills they pay. The renters' forms, which are also available at Maryland Offices on Aging, are for refunds for elderly or disabled renters. For information on the program, call 800-492-3790.

Attorney Benny L. Kass will conduct a workshop on condomium buying and selling in Washington in Maryland from 10 a.m. to 1 p.m. Feb. 9 at the Wellington Hotel, Wisconsin Avnue and Calvert Street NW. The fee is $35. For information, call 966-5703.

Satellite Business Systems, a Northern Virginia firm that had planned to build a headquarters building in Reston, will move instead from its current four locations to a building in Tysons Corner. Robert C. Hall, president of the advanced communications company, said the firm will lease nine floors of an 11-story building being developed by David Evans at 8283 Greensboro Rd. The 10-year lease is for more than $20 million.

Columbia Technical Institute in Arlington is offering a new semester of adult courses in building construction starting Monday. Among the subjects are building construction estimating; the national electrical code; heating, ventilation, air conditioning and refrigeration, and others. For information, call 920-8866.

The Maryland Senate gave preliminary approval this week to a bill that would boost the interest rate landlords must pay on tenants' security deposits. The legislation would increase the rate to 4 percent. It has been 3 percent since 1972.