ASP.NET pages can contain no more than one HTML form and 
can post only to itself, but you can work around this 
limitation to add extra input forms



How can I use multiple HTML forms in an ASP.NET 
application? How can I build a page to make it contain a 
small form in a corner for users to login or start a 
search? These are frequently asked questions from those who 
do serious ASP.NET development. The problem arises from the 
fact that ASP.NET forces a single-form programming model. 
In HTML, the form is the construct designed to gather some 
input data and post it to the server for further 
processing. The form is seen as a collection of <input> 
tags such as textboxes, drop-down lists, and checkboxes, 
whose contents are automatically collected and posted when 
a submit button is pressed. Likewise, the same finalizing 
process can be started via script. In HTML, you can have as 
many forms as you like in each and every HTML page. This 
structure has been maintained in Active Server Pages (ASP), 
mostly because ASP is a sort of wrapper built around the 
HTML page. In the end, with ASP you create the page 
structure from an HTML basement with some opened windows of 
dynamically generated markup. 

ASP.NET is quite different and qualifies as a true runtime 
environment that enforces its own programming rules to 
generate the same kind of output—HTML markup. In doing so, 
ASP.NET mandates that, at most, one form is supported, and 
any submissions the web server can receive from a page 
should target the same original URL. In short, each ASP.NET 
page can contain no more than one HTML form and can post 
only to itself. 

There are many benefits to the ASP.NET programming model 
out of this pattern, the most important of which is the 
ability to handle postback events on top of a stateful 
architecture. In ASP, how did you manage to maintain the 
state of input elements across two successive requests for 
the same page? Should I say it? I guess you were forcing 
the action attribute of the HTML form to the same URL of 
the current page and using some code blocks and the session 
state to restore key attributes on input fields. At its 
core, this is just what ASP.NET does, except that it uses 
viewstate instead of session state and that it promotes the 
model to rank of a “mandatory” rather than “optional” 
feature. 

In summary, to be able to use ASP.NET server controls for 
capturing some user input, you have to use the ASP.NET 
server form control. In doing so, you lose the power of 
controlling the action attribute of the form and are 
limited to, at most, one form per page.

Hence the initial question, how can you insert a second 
form in an ASP.NET page? 

If your goal is “changing” the form from time to time, 
obeying different runtime conditions, then be aware that 
the enforced rule states that only one form can be visible 
at any time. So you can place as many as <form 
runat=server> tags as needed in a page, as long as only one 
of them is marked with visible=true. By acting on the 
visible attribute, you can programmatically switch from one 
form to the next. 

If your goal is having a “child” form for login or search 
purposes, the solution is even simpler: Stick to classic 
HTML forms; that is, <form> tags devoid of the runat 
attribute. ASP.NET doesn’t exercise any control on tags not 
marked with the runat attribute and you’re just fine until 
HTML supports multiple forms. What do you lose in the 
change? The ability of using postbacks in the target page 
of the login or search. Just use the ASP classic 
programming model—the Request object—and you’re all set.

Yes we can do it