I am interested in an apartment that is a combination of two one bedrooms. The owner has physically combined the unit - meaning there is only one entrance, one kitchen etc. However, the owner does not have any other paperwork in order ( no "C of O", tax lots are still separate etc). Will I get a single mortgage assuming that I buy the property as-is and then work with the Board, the Department of Finance and DOB to get all the approvals? Also, how long does the paperwork take to legally combine the units and what is the associated cost? Any ideas on how this can be worked out. Thanks.

This is a question for your lawyer.

You provide very little information for anyone to speculate. This can turn into a complex situation. For example would you have to make the units comply with ADA laws? DOB permits are complicated to go through. Prior to consulting with a lawyer, an architect might help in understanding the process to combine units and change the CO. However, I would start by asking the current owner for the reason he did not combine the units legally. Not that the owner will necessarily disclose the real reasons.On the other hand, since you mention the BOARD, it sounds like this might be a coop with very easy (or unsophisticated) Board.

Since tax lots were mentioned, it's a condo, not a co-op.

The building doesn't need a new C of O, since there was no change in "occupancy or egress."

The condo board can combine the tax lots by filing a simple amendment to the condo declaration, and amended plans.

You mortgage closes at the same time as the sale, so it'd cover the existing two lots.

There're probably lots of other issues, so just see a lawyer, as Riversider said.

If your lender's OK with it as two lots, it'd be no big deal to let it slide for a while. I've seen several combos that were never combined, get two tax bills, etc.

Here're samples of amended declaration and plans:

http://a836-acris.nyc.gov/Scripts/DocSearch.dll/Detail?Doc_ID=2012092400126002
http://a836-acris.nyc.gov/Scripts/DocSearch.dll/Detail?Doc_ID=2012092400126001

Thank you all for your responses- very helpful! Thank you@NWT for your insight and the ACRIS details. As NWT mentioned, this is a condo. I do not have much information from the broker on why the owner hasn't combined the units - other than, it will take them several (~6) months to do the paperwork. Owner is prepared to negotiate on the selling price if I were to do the paperwork myself.

It is not unusual, at least in small condos, to keep the tax lots seperate. The amendment to the condo declaration is more hassle than is necessary, and combining the tax lots is meaningless. However, you do need a CofO for the combined units. Your lender likely will not lend against the separate units.

In our seven story loft building, only two floors still have the original two apartments, the other five have been combined (in one instance, spanning floors). Everyone has a CofO for the combined units, but none of the tax lots have been merged. Geting the CofO should not be a big deal if no bathrooms or kitchens were moved (raising ADA compliance issues), but it is a wrinkle you likely will have to deal with assuming that you are financing.

NYC hasn't required a new CofO for combos since 1997.

If there's a change in occupancy, e.g. in a building where some floors are changing from commercial to residential use, then it's still required. Not for combining two or more apartments into one.

Since it's a condo then you must first combine them with the DOB. You need an architect to do this after-the-fact. And you'll need the condo board to review drawings and approve after-the-fact also. Then the architect has to do new tax lot drawings to be filed with the Dept of Finance. Also must file a revised condo declaration in tandem with the drawings, so you'll need a lawyer for that (the condo's lawyer did this for us a while ago). It was a long, long process. Figure 6 months to a year (DOF is very slow). You would have to figure that the owner had an architect to do the combo but just didn't follow through with the tax lots. Maybe he can finish it for you. If not, I can put you in touch with the arch that did it for us.

Also, the other commenter was correct - you don't have to amend the c of o.

we did this in 2008 and are combining a 3rd apartment in 2012 BUT we were in a co-op

easy peasy.

Single mortgage etc just treated like a single apartment but each time we did a combination they hold a "escrow" to make sure you do the renovation to join them together, once you do this and get it signed off by the city you get the funds returned to you.