The NIH Format Attachment guidance on the How to Apply - Application Guide page has included the same rules for filenames for many years. Filenames used for grant application attachments must be

• descriptive;
• unique within an application (or within a component of a multi-project application);
• comprised of the following characters: A-Z, a-z, 0-9, underscore, hyphen, space, period, parenthesis, curly braces, square brackets, tilde, exclamation point, comma, semi colon, apostrophe, at sign, number sign, dollar sign, percent sign, plus sign, and equal sign; and
• 50 characters or less (including spaces).

HOWEVER -  eRA systems will now enforce the 50-character limit for filenames used for attachments in grant applications. As a point of reference … This is 50 characters with spaces and punctuation. You can convey a surprising amount of information in 50 characters, but maybe not as much as you want. For example, “consortium-contractual-arrangements-institution-pi-name” is over the limit and its use would result in an error.

The new validation will be part of the business rules checked by ASSIST and other solutions that use the validation service pre-submission. If you think you might be pushing the 50-character limit, run a quick Validate Application (if using ASSIST), Preview Grantor Validation (if using Workspace), or whatever your system-to-system solution calls it and make any necessary adjustments. If the long filename isn’t caught prior to submission, you know NIH will catch it after submission.

No one wants to be left scrambling to rename and reattach files at the last minute.