I married a U.S. citizen, and am now a conditional U.S. resident. However, my husband has been temporarily posted to an overseas job, and I am living with him. The two-year deadline for filing my Form I-751 to remove the conditions on residence and get me a permanent U.S. green card is coming up soon. Is this deadline the same even though I'm outside the United States? If so, can I submit Form I-751 from another country? What will happen next? Will I need to go back to the U.S for things like the biometrics appointment or an interview?
The first thing to look into, as a conditional resident living overseas, is whether you face any risk of losing your U.S. residence altogether, by having "abandoned" your residence. This is a particular risk if you remain outside the U.S. for more than a year. See Keeping Your Green Card After You Get It, and consider consulting an immigration lawyer in the U.S. for a personal analysis.
And yes, the two years tick by at the same pace regardless of where you are living, so you need to pay attention to that upcoming deadline.
Assuming abandonment is not an issue, conditional residents are indeed legally allowed to submit the required USCIS Form I-751 from outside the United States. You would send it to the USCIS facility having jurisdiction over your last U.S. place of residence.
But you will absolutely need to be in the U.S. for your biometrics appointment and to attend an interview, if U.S. Citizenship and Immigration Services (USCIS) asks you to do so. (Luckily, most applicants filing joint I-751s with their spouse, rather than filing solo and asking for a waiver, are not asked by USCIS to attend an interview.)
One possibility, if you know that you'll be returning to the U.S. before too many months go by, is to accompany your I-751 with an explanation of where you are now, and a request that final decision-making on your case be postponed until you have returned to the United States.
You will need to get the fee receipt from USCIS, however, showing filing of your I-751, in order to return to the U.S. and be admitted at the border or other point of entry. You'll show your right to return using the receipt and your expired green card.
In fact, upon seeing an overseas address, USCIS is likely to simply assume that you won't be available for biometrics or an interview and put your case on hold. If you want to avoid this, and you continue to have a valid address in the U.S. and are prepared to return to the U.S. as soon as appointments for biometrics and an interview are sent to your U.S. address, you might want to list that address on your I-751 application.
To avoid complications during this process, it would be wise to hire an experienced U.S. immigration attorney.