Authorisation and separate clients
Corppass Corporate Tax (Filing and Applications) Preparer prepares and sends to an Approver; only an Approver may complete, approve and file to IRAS. An agent must submit each client separately; File for Next Client starts a similar transaction after finishing the first.
Document checklist by last filing
ECI requires only the revised ECI amount. After C-S/Lite, prepare original tax computation/schedules and original audited or unaudited accounts with detailed P&L, plus revised computation/schedules and revised accounts where applicable. After Form C, prepare revised computation/schedules, applicable revised section 19B IPR allowance declaration, R&D claim and related-party-reporting form, plus revised accounts if applicable. Upload VD supporting material with the revised computation.
PDF format and size
Each document must be a non-fillable PDF no larger than 4MB; all files per YA submission no larger than 10MB. The FAQ recommends readable 100dpi black-and-white or lower-resolution copies. Print Word/Excel/fillable PDF through Microsoft Print to PDF to remove active content such as e-signatures; it explicitly advises against simply Save as PDF for those files.
Service choice, revision limits and years
Select Corporate Tax → Revise/Object to Assessment. Only ECI filed displays Revise/Object to ECI; a form under review displays Revise Form Filing; a finalised form assessment displays Object to NOA. There is no numerical limit on ECI or form revisions, though some ECI cases request reasons instead of letting you edit. Both routes cover current YA, one advance and four prior YAs up to the time bar.
Different approval and draft periods
An ECI Approver has 14 days, after which its record is deleted and must be prepared again. For forms, saved drafts and pending approvals expire after 21 days; approval must occur within that period. Disabled fields are intentionally not required; proceed to enabled fields. Risk-based assessment explains differing requests across YAs.
Form conversion and source inconsistency
The PDF contents lists Q16 as C-S/Lite to C, but its actual Q16 answer describes C to C-S/Lite. That operative answer says the initial form determines display; after initial Form C, choose Yes at the qualifying-conditions prompt to revise/object through C-S/Lite. The opposite conversion is not resolved by that answer and should not be inferred from the contents heading.
Preloaded figures and long first periods
C-S/Lite filed on/after 23 September 2020 preload previous figures. Earlier filings preload zero except brought-forward allowances/losses/donations and current-year donations. Last-filed Form C preloads regardless of that date. For a disabled basis period, choose Change in basis period/Claiming Loss Carry-Back Relief at Getting Started. A first basis period longer than twelve months can make Part B’s first four fields differ from the adjusted-profit subtotal: allocate to the particular YA by direct identification or time apportionment.
Group Relief and Loss Carry-Back
Group Relief applications are final and irrevocable, but data can change where tax position changes from taxable to loss or vice versa; unchanged positions may be rejected. To claim carry-back, choose the same basis-period/carry-back reason and supply revised computation/schedules. Ordinarily elect by filing due date and election is irrevocable. The FAQ permits an election after taxable-to-loss change but warns rejection if no position change or election later than two months from service of the NOA reflecting that change.
Acknowledgement, navigation and timeout
Retrieve acknowledgements through Notices → Corporate Tax within three working days of filing. Use the service’s bottom Back button, not browser Back. After over fifteen minutes inactivity a two-minute prompt appears, then automatic logout if still inactive.
Error reporting and edition
Clear browser cache and close active applications before retrying. If unresolved, send myTax Mail with error date/time, company and filer tax references, action/location of error, message/screenshot, operating system and browser/version. This article follows the FAQ updated 5 May 2025.
Official source
This article independently explains the substantive contents of the official PDF, including the relevant conditions, procedures and annexes. The linked document remains the authoritative source for its original wording, and later changes should be checked separately.
Read the official PDF ↗