Depending on the outcome of a current court case, persons who paid an unincorporated business tax during 1975 in the District may be eligible for a refund.

But the persons involved-those who paid a tax imposed on professionals and personal service businesses-must file a refund claim by April 16.

The District government was directed by D.C. Superior Court to notify persons who paid the taxes in the first 11 months of 1975. It is not known when the court will issue a decision in the case.

Involved in a legal battle is the unincorporated business tax for such professionals as physicians, lawyers and architects practicing in D.C.

The court has upheld the validity of the tax but implementation of the tax during the first year (1975) was judged unlawful because calendar-year taxpayers and fiscal-year taxpayers were charged differently. Both decisions have been appealed and whether any refunds will be made depends on the outcome of the court appeals.

Persons who paid taxes during the period at issue must file a refund claim under oath by April 16 to remain eligible for any refunds that are made.

Questions about eligibility should be directed to Philip Kellogg or James Lyons at 785-8292 or Bradley McDonald at 338-7800, lawyers for the taxpayer class in the suit. Refund claims are available at the D.C. Department of Finance and Revenue, Room 2053, 300 Indiana Ave. NW.