Form IT-203-S-ATT (2025): Attachment for New York Group Nonresident Returns

Form IT-203-S-ATT is a supplemental schedule issued by the New York State Department of Taxation and Finance for use alongside Form IT-203-S, the Group Return for Nonresident Partners and Shareholders. If your partnership or S corporation is filing a group nonresident return and has more participating partners or shareholders than fit on the main form, this attachment is where the extra names, identification numbers, and income allocations go.

New York allows certain partnerships and S corporations to file one consolidated group return on behalf of multiple nonresident partners or shareholders, rather than requiring each individual to file a separate IT-203 nonresident return. This saves paperwork for both the taxpayers and the state, but it only works if every eligible participant is properly listed with their share of New York source income, tax computed, and other required details. When the group has a large number of participants, Form IT-203-S alone doesn’t have enough room, and that’s exactly the gap Form IT-203-S-ATT fills.

Who needs to file this attachment

You’ll need Form IT-203-S-ATT if your entity is preparing a group nonresident return under IT-203-S and the number of participating nonresident partners or shareholders exceeds the space provided on the base form. Tax preparers handling multi-member partnerships or S corporations with dozens of nonresident owners are the ones who typically encounter this. Each participant listed on the attachment must meet the same eligibility rules that apply to the main group return: they must be nonresidents of New York for the entire tax year, have no other New York source income outside their share from the entity, and agree to be included in the group filing instead of filing their own IT-203.

This is distinct from situations involving a nonresident or part-year resident spouse, which is handled separately through Form IT-203-C. That form deals with spousal certification on an individual joint return, while IT-203-S-ATT is strictly about expanding the list of participants on an entity-level group filing.

When it’s used

The attachment is filed for tax year 2025 at the same time as the main IT-203-S, as part of the entity’s annual filing obligation. There’s no standalone filing scenario for IT-203-S-ATT — it never gets submitted on its own. If the entity’s participant list changes from year to year (new partners added, others dropping off nonresident status), the attachment needs to be updated annually to reflect the current group makeup.

Timing follows the same deadlines as the underlying partnership or S corporation return. Missing the deadline or omitting a participant from the attachment can create complications, since any nonresident partner or shareholder not properly included may end up needing to file an individual return instead.

How to complete and submit it

Form IT-203-S-ATT is available as a fillable PDF directly from the New York State Department of Taxation and Finance website. Because it has AcroForm fields, you can type participant names, identification numbers, and income figures directly into the document on your computer before printing or saving it, which cuts down on manual errors compared to filling it out by hand.

For each additional partner or shareholder, you’ll need their full legal name, Social Security number or EIN, their allocated share of New York source income, and the tax calculated on that share. The totals from the attachment need to tie out with the summary figures reported on the main IT-203-S form, so it’s worth double-checking the math before submission. Preparers who work across multiple state entity filings, including those handling comparable exemption paperwork like California Form 3500, know that consistency between attachment schedules and the primary form is one of the most common places reviewers flag mistakes.

Once completed, the attachment is submitted together with the IT-203-S as part of the same filing package, whether that’s done electronically or by mail depending on how the entity files its group return. Keep a copy of both the main form and the attachment for your records, since individual partners or shareholders may need documentation confirming they were included in the group filing for their own tax records.