Calculate annual salary of an employee by input of employee’s monthly salary and commission

CREATE FUNCTION dbo.fn_Annualsal ( @p_sal DEC(9,2), @p_comm DEC(5,2))
RETURNS FLOAT
BEGIN
	DECLARE @v_ann_sal FLOAT = 0.0, @v_sal DEC(9,2)= COALESCE(@p_sal, 0.0);
	SET @v_ann_sal = (@v_sal + @v_sal*COALESCE(@p_comm, 0.0))*12
	RETURN @v_ann_sal
END
GO

-- Test
SELECT dbo.fn_Annualsal( 6000, 0.15)
SELECT dbo.fn_Annualsal( 1500, NULL)