Exporting PDF within the margins

Hmmm...the longer this goes, the more convoluted it seems to get because it's not clear whether we're all using the same terms in the same ways. So let's try it like this:

The Page - The actual physical media size; for this exercise, US letter, 8.5w x 11h:

The Margins - A designer-set distance from the edges of the page; here we'll say it's 1/2 (0.5) inch (in gray, outside the red margin guides) on all sides:

The Image Area - The area inside the margins (in yellow, inside the red margin guides), which in this case would measure 7.5w x 10h:

"we design within the margins"

Okay so there's no need to explore "bleed," presumably.

So using those definitions, your question:

"Is there a way to only export the image area within the margins."

No, PDF Export from InDesign exports the Page Size + bleed if specified. (It will also add to the media size for crop/printer's marks if specified.)

So, if the Image Area (yellow above) is really what your printer wants (although it makes little sense, and I strongly suspect that is not what they want), the way I'd do that is by cropping all pages down to that size in Acrobat, post-export.

 I'm not sure that it's totally unreasonable, but could be a communication problem. Suppose (for example) that the finished piece will be 8.5x11 with 1/2" margins on all sides, and that there shouldn't be anything within the margins. Here's an example where two text frames are completely within the margins:

…but because of the stroke and drop shadow, it's leaking into the margins. If the printer had to fit this into the live area, it would either look like this:

…or would have to be reduced to fit. Setting aside whetheror not a "no copy in the margins" requirement is reasonable or not, but designing to the live area instead of the page size would alert the designer that if something is off the page, it won't be printed. Just my 2¢.

Are you sure they are not confusing you the wrong term? Maybe by margin they mean the area that the Printer Marks occupy?

In this example you obviously couldn't remove the margin or bleeds because they are both needed, but you could export with no printer marks and remove the space outside of the bleed:

I think what is needed here is additional communication with your printer. As Mike and John have said this is not a reasonable request for the printer to make. Find out specifically what the printer actually needs in order to export your job and why they need it. When dealing with printers it is essential to get every bit of information they have so that you can prepare your work for output in a way that is absolutely "bulletproof". Communication is at times the most important step in any production. 

"We recently switched printers and they requested only the image area as the final export."

Unfortunately, I'd say that indicates you need to swtich yet again.

PDF export is not selective in that way, and your options for making it work under such a silly demand are limited:

• Change the page setup to effectively 'clip' the page size to the current margins
• Crop in Acrobat post-export

It seems to me that the matter might be misunderstood. No one would ever require a document that way. Maybe they just mean to turn off the bleed and printer's marks? I don't know, but that doesn't sound sensible.