Is there a legal time limit to when a Deed of Trust is suppose to be filed?

Hi. I am a Maryland barred attorney and write in response to your post.  The Deed of Trust should be recorded promptly after settlement.  Generally, this wil be done by the title company who conducted the settlement within a few days or weeks.  Keep in mind that it sometimes takes the county/city a little time to process filings, so it might be a bit after filing that the Deed of Trust shows up in the Land Records.  

However, if it has been a long time (months or years) after your settlement and the Deed of Trust wasn't recorded, I'd strongly encourage you to have an attorney review the transaction.  I hope this helps.

There is no such legal time limit; in fact a Deed of Trust does not have to be filed at all. 

Basically, a Deed of Trust secures a lender's interest in a specific property; if the borrower defaults on their underlying Note obligation to the lender, the lender will then have a priority claim to the property.  Once it is recorded no claim can be superior or ahead of the lender's interest.  So, for example, if the borrower tried to sell the property, clear title could not be conveyed to a purchaser until the lender released their claim (Deed of Trust) to such property.  And it would not do so until it recieved a payoff on the Note (typically out of the sale proceeds).

If a Deed of Trust was not recorded then the lender would still owe on the Note, but in the event of default on the Note, the lender would have to chance that the property had not already been sold (and the borrower had not already spent the sale proceeds).  In that case, the lender would have to hope the borrower had other assets from which to satisfy any amounts still owing under the Note and that other creditors had not already made claim to them.

So, as a practical matter, while a Deed of Trust does not have to be recorded, it almost always is at the time that the Note is executed so that a lender is able to "perfect" their security interest.