Suppose the following:
- You filed an I-140 PERM petition, which is approved but for which a visa number is unavailable.
- At some point after the I-140 approval, the visa bulletin shows the case has becomes current and an I-485 is filed.
- One day after the I-485 is pending, suppose the beneficiary marries an American citizen and files an I-130.
- Two months into the I-485 filing, the I-140 PERM category suffers visa retrogression, and his case is no longer current.
- The I-485 case is put on hold as at time of adjudication the case cannot be issued.
- The I-130 is approved.
- What do you do about the existing I-485? As an immediate relative petition, there is no delay, but the I-485 was filed based on the I-140 PERM petition.
The answer is what USCIS calls “Transfer of Underlying Basis”, which is detailed in 7 USCIS-PM, Pt. A, Ch. 8.
One has to make this request in writing and provide evidence of eligibility in the new category. “The transfer request should be treated as if it were a new filing and the applicant should provide the necessary documentation to establish eligibility for the new adjustment category.” 7 USCIS-PM, Pt. A, Ch 8. Section A-3. This issue can come up if one doesn’t want the “conditional permanent residency” caused by LPR status through marriage, or conversely, if waiting for an employment-based petition would take longer than through the immediate relative status.
There are certain things to keep in mind. First, the original reason for the I-485 has to still be there. For this hypothetical, to have “continuing eligibility to adjust status” means the underlying I-140 PERM has to still be true. You cannot transfer the basis of an I-485 if the original I-485 is based on a basis that is no longer there.
Second, there cannot be any “funny business”. By this, I mean the first petition should not be fraudulent, cannot be withdrawn or denied, or revoked. You also have to be eligible for the I-485 based on the second petition as if it was a new I-485, meaning the priority date is current for the second petition and there are no immigration bars (since marriage AOS have less bars to AOS than employment AOS).
Transfer of basis is a discretionary matter for USCIS. They could say no, and USCIS is suppose to figure out if this works out better or worse in terms of processing. If this would cause significant processing delays, USCIS can say no. As a potential example, suppose a mainland Chinese case has an approved EB-1A, files the I-485, the category suffers retrogression, and while the I-485 is still pending, an I-130 through her American Citizen sibling is approved. A request to change the basis of the I-485 from employment category 1(with a wait time of around a year) to family sponsored 4 would probably be denied (with a wait time of around 13 years).
In short, this means another I-485 does not need to be filing, thus saving the client from paying additional filing fees. However, each I-485 can only have one underlying basis, and which basis is used must be clearly “designated in writing”. In concurrent filing scenarios, one may also transfer a previously filed I-485 to the new petition, by stating in writing that they will use a previously filed I-485 (details on how contained in the Policy Manual). This also means an I-485 basis can be transferred from a petition that is already approved to a petition that is pending, although as a practical matter this is probably not a good idea (waiting for approval before making this request would be the better idea). One should also remember transferring basis for a third time is not permitted.
Da Kine Law 
You can transfer an I-485 to a second, later-filed petition (with multiple caveats)
Suppose the following:
The answer is what USCIS calls “Transfer of Underlying Basis”, which is detailed in 7 USCIS-PM, Pt. A, Ch. 8.
One has to make this request in writing and provide evidence of eligibility in the new category. “The transfer request should be treated as if it were a new filing and the applicant should provide the necessary documentation to establish eligibility for the new adjustment category.” 7 USCIS-PM, Pt. A, Ch 8. Section A-3. This issue can come up if one doesn’t want the “conditional permanent residency” caused by LPR status through marriage, or conversely, if waiting for an employment-based petition would take longer than through the immediate relative status.
There are certain things to keep in mind. First, the original reason for the I-485 has to still be there. For this hypothetical, to have “continuing eligibility to adjust status” means the underlying I-140 PERM has to still be true. You cannot transfer the basis of an I-485 if the original I-485 is based on a basis that is no longer there.
Second, there cannot be any “funny business”. By this, I mean the first petition should not be fraudulent, cannot be withdrawn or denied, or revoked. You also have to be eligible for the I-485 based on the second petition as if it was a new I-485, meaning the priority date is current for the second petition and there are no immigration bars (since marriage AOS have less bars to AOS than employment AOS).
Transfer of basis is a discretionary matter for USCIS. They could say no, and USCIS is suppose to figure out if this works out better or worse in terms of processing. If this would cause significant processing delays, USCIS can say no. As a potential example, suppose a mainland Chinese case has an approved EB-1A, files the I-485, the category suffers retrogression, and while the I-485 is still pending, an I-130 through her American Citizen sibling is approved. A request to change the basis of the I-485 from employment category 1(with a wait time of around a year) to family sponsored 4 would probably be denied (with a wait time of around 13 years).
In short, this means another I-485 does not need to be filing, thus saving the client from paying additional filing fees. However, each I-485 can only have one underlying basis, and which basis is used must be clearly “designated in writing”. In concurrent filing scenarios, one may also transfer a previously filed I-485 to the new petition, by stating in writing that they will use a previously filed I-485 (details on how contained in the Policy Manual). This also means an I-485 basis can be transferred from a petition that is already approved to a petition that is pending, although as a practical matter this is probably not a good idea (waiting for approval before making this request would be the better idea). One should also remember transferring basis for a third time is not permitted.