Model-view-viemodel pattern
public class TaxGroupDataModel : DataModel
{
    private readonly TaxGroup _taxGroup;
    private readonly IEnumerable<TaxSubGroup> _taxSubGroups;

    public TaxGroupDataModel(TaxGroup taxGroup)
    {
        if (taxGroup == null) { throw new ArgumentNullException("taxGroup"); }


        _taxGroup = taxGroup;
        _taxSubGroups = taxGroup.SubGroups;
    }

    public IEnumerable<TaxSubGroup> TaxSubGroups { get { return _taxSubGroups; } }

    public TaxGroup TaxGroup { get { return _taxGroup; } }
}