What HMRC says
HMRC's guidance says that if you get an error message beginning "ASM", you should make sure you have not copied and pasted into the Gift Aid spreadsheet, and that you have saved the file as an OpenDocument Spreadsheet (.ods).
Why pasting causes trouble
When you paste from another spreadsheet, you usually bring that sheet's formatting with you: different cell types, hidden characters, or dates stored as text in another layout. The schedule looks right on screen, but the file underneath no longer matches what Charities Online expects.
How to fix it
- Download a fresh copy of the template from GOV.UK. Pick the version for the software you use (see which template to use).
- Type the donations in, or use your spreadsheet program's "paste special" option and choose unformatted text or values only, so formatting does not come across.
- Save it as an .ods file. Do not rename the extension by hand.
- Upload it again.
How Donor Schedule avoids it
We do not paste anything. We write each value into HMRC's own template cell by cell, using the template's own cell styles, and leave the rest of the file exactly as HMRC made it.
This page is general guidance based on HMRC's published schedule spreadsheet guidance and template, checked on 20 October 2026. It is not tax advice, and HMRC's own pages take priority if they change. Donor Schedule is not affiliated with HMRC.
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