2026 IRS Changes Affecting Family Business Write-Up

Every year the IRS refines its guidance on write-up and accounting services — but 2026 brought changes significant enough that family business owners need to act now rather than wait for tax season. At Parsi & Company, we've reviewed the updated guidelines and want to share what matters most for our clients in Los Angeles and Century City.

What Changed in 2026

The IRS updated its guidance across three primary areas that directly affect how family businesses must document their accounting and write-up services. These aren't just administrative tweaks — they affect how deductions are supported during an audit and how income is characterized.

1. Substantiation Requirements for Write-Up Expenses

Starting January 1, 2026, the IRS now requires more granular documentation for write-up and bookkeeping expenses claimed as business deductions. Specifically, businesses must maintain records that show the nature of each service rendered, not simply the invoice total. A monthly bookkeeping invoice from your CPA firm must now be accompanied by a brief description of services rendered that quarter.

2. Changes to How Write-Up Income Is Reported for Pass-Through Entities

For S-Corporations and Partnerships — the most common structures among our family business clients — there are updated rules around how write-up income received through pass-through arrangements must be characterized on K-1 statements. Incorrect classification here is one of the most common triggers for IRS correspondence audits in 2026.

3. Updated Preparer Requirements

Any write-up service that affects a tax return must now be performed or supervised by a credentialed preparer — either a CPA, EA, or attorney. This formalization of oversight requirements means family businesses that used uncredentialed bookkeepers for write-up work may face challenges substantiating those deductions.

What You Should Do Right Now

If you're a family business owner working with Parsi & Company, we're already reviewing your write-up documentation structure as part of our 2026 planning process. If you're not yet a client, here are the immediate steps you should take:

1. Review every write-up invoice from your current bookkeeper and confirm it includes a description of services — not just a total fee.
2. Confirm that whoever performs your write-up services holds a valid CPA, EA, or attorney credential.
3. Review your K-1 statements from 2025 with your CPA to ensure write-up income was characterized correctly before the 2026 rules are applied retroactively in an audit.
4. If you're using accounting software for self-managed write-up, ensure your records export contains enough detail to satisfy the new substantiation standard.

How Parsi & Company Is Responding

For all of our current write-up clients, we've updated our engagement documentation to include the service detail now required by the IRS. We've also built an internal review process to verify K-1 characterization of write-up income before any return is filed in 2026.

If your business has write-up arrangements that weren't handled through Parsi, we recommend scheduling a review before your next quarterly filing to identify any exposure.