To create the checkbox with the rule, first, create the checkbox tabs and associate them with the TabGroup through the TabGroupLabels. In the TabGroup object, you can specify the checkbox rule through the GroupRule, MinimumRequired, and MaximumReqiured properties. More information about the available value for the above properties is here: https://developers.docusign.com/docs/esign-rest-api/reference/envelopes/envelopes/create/#schema__envelopedefinition_recipients_signers_tabs_checkboxtabs_required

C# code example below allows the recipient to select only one checkbox between 3 of them.
 

Checkbox checkbox1 = new Checkbox
{
    TabLabel = "LionTab",
    DocumentId = "1",
    PageNumber = "1",
    RecipientId = "1",
    XPosition = "200",
    YPosition = "300",
    TabGroupLabels = new List<string>
    {
        "checkboxgroup1"
    }
};
Checkbox checkbox2 = new Checkbox
{
    TabLabel = "TigerTab",
    DocumentId = "1",
    PageNumber = "1",
    RecipientId = "1",
    XPosition = "220",
    YPosition = "300",
    TabGroupLabels = new List<string>
    {
        "checkboxgroup1"
    }
};
Checkbox checkbox3 = new Checkbox
{
    TabLabel = "BearTab",
    DocumentId = "1",
    PageNumber = "1",
    RecipientId = "1",
    XPosition = "240",
    YPosition = "300",
    TabGroupLabels = new List<string>
    {
        "checkboxgroup1"
    }
};
TabGroup checkboxTabGroup = new TabGroup
{
    GroupLabel = "checkboxgroup1",
    ValidationMessage = "Please check a box",
    GroupRule = "SelectExactly",
    MinimumRequired = "1",
    MaximumAllowed = "1",
    RecipientId = "1",
    DocumentId = "1",
    PageNumber = "1",
    XPosition = "0",
    YPosition = "0",
    TabScope = "Document", // or "envelope"
    TabType = "tabgroup"
};

Tabs signer1Tabs = new Tabs
{
    SignHereTabs = new List<SignHere> { signHere1 },
    CheckboxTabs = new List<Checkbox> { checkbox1, checkbox2, checkbox3 },
    TabGroups = new List<TabGroup> { checkboxTabGroup }
};

signer1.Tabs = signer1Tabs;

Thank you for the reply, It is working at the submitting of the document can we make this checkbox function like radiobutton.

I do have a similar scenario in which i have two sets of “Yes” “No” checkboes.. 

I created two tabgroups  namely checkboxgroup1 and checkboxgroup2 and have 4 checkboxes as outlined below..

checkbox1 with the tablables property set to “TabGroupLabels = new List<string> { "checkboxgroup1" }”

checkbox2 with the tablables property set to “TabGroupLabels = new List<string> { "checkboxgroup1" }”

checkbox3 with the tablables property set to “TabGroupLabels = new List<string> { "checkboxgroup2" }”

checkbox4 with the tablables property set to “TabGroupLabels = new List<string> { "checkboxgroup2" }”

By having the same, it only work for the bottom group and make the first two checkboxes “optional”..

any help would be much appreciated.. 

by not setting the “RecipientID” of those tabgroups helped me to fix the issue.. thanks..