Write-up is not a monthly that happens once
I still see engagement letters that say "bookkeeping" and mean a shoebox in March.
Write-up is closer to reconstruction: source documents for a closed period, a rebuilt year, statements the preparer can file. Monthly CAS is a current close, every month, with review baked in. Pricing them like the same seat is how you lose money on both.
Catch-up vs monthly is the same split with different labels. The real math behind a bookkeeping service line is the monthly version of the margin conversation.
When I call it write-up or reconstruction
- The client shows up with statements after year-end
- There is no current close
- The software file is a year late or missing
- The output is filing-ready historicals, not a monthly pack
That work belongs on tax deadline reconstruction or reconstruction for tax professionals. What catch-up bookkeeping costs is the quote logic: diagnostic, then a fixed number. IRS recordkeeping rules still apply.
When I call it monthly CAS
The books are current enough to close this month. You want a recurring package under the firm's brand. Partners review instead of producing. For CPA Firms and how it works are that product. Practice it on a free test client.
Sample deliverables is the monthly pack. Do not use it as proof that an annual write-up was delivered. A rebuild includes those statements per year. A CAS engagement includes them per month.
Why firms blur them
Capacity. Write-up feels like "we will get to it." Monthly feels like a hire you do not have. AICPA hiring-outlook reporting is the backdrop. Blurring the products does not create the people.
Scope the historical year as reconstruction. Subscribe the current year as monthly. When not to outsource bookkeeping covers the tax-only monthly misfit.
Price the job you are actually doing
Get a reconstruction quote for write-up years. Start a free test for a current CAS client. Do not send both through the same ticket and hope the margin holds.