Registry

HMRC 64-8 — programmatic fill compatibility

Authorising your agent · HM Revenue & Customs (HMRC) · HMRC 05/25. Tested 2026-08-06 on the unmodified upstream blank — every number below comes from a recorded run, not from documentation.

Verdict at a glance

Tool	Version	Result	Detail
pdfops API	hosted, tested 2026-08-06	verified + deterministic flatten	76/76 supported fields landed; flatten=true byte-deterministic (sha256 a1b9fc23a24f…)
pdf-lib	1.17.1	verified (76/76)	76 fields filled in-process
@cantoo/pdf-lib (fork)	2.6.5	verified (76/76)	76 fields filled in-process
pypdf	6.15.0	text fields verified (59/59)	59 text fields written and re-read (text fields only)
pdftk-java	3.3.3	verified (76/76)	76 fields filled via FDF and re-dumped
qpdf --check	11.9.0	warnings	WARNING: public/registry/blank/hmrc-64-8.pdf: page 2: shared object 570: in hint table but not computed list \| qpdf: operation succeeded with warnings
poppler render check	24.02.0	values render (59/59)	59/59 filled text values present in pdftotext output of the pdf-lib-filled file; page-1 raster sha256 0c08158ddb19…

File facts

Source: https://assets.publishing.service.gov.uk/media/6852e9f02b367fdd44c15e8a/64-8.pdf (issuer page: here)
Blank tested: hmrc-64-8.pdf · 1038 KB · sha256 9b52438ecc4d9e4aa4e67d4a61c21043b5419b755c111dcddf76b9fb1abaafc4
License: Crown copyright, published under the Open Government Licence v3.0. The hash-verified blank is redistributed here unmodified.
Structure: 3 pages · AcroForm
Fields: 77 (59 text, 17 checkbox, 1 button)

Quirks & limitations

The first non-US, non-XFA jurisdiction in this registry: a plain AcroForm (no XFA layer at all) from HMRC, the UK's tax authority — useful as a check that this registry's US-federal-heavy findings (XFA drop, maxLength enforcement) generalize outside the IRS/USCIS family rather than being an artifact of US agencies' specific tooling.
A4 page size (595 x 842pt), not US Letter — a real-world reminder that page-geometry assumptions baked into a filler (e.g. fixed-DPI raster preview sizing) can't be hardcoded to Letter.
Carries field-level JavaScript (/AA actions) like the US federal forms in this registry, but built with Adobe InDesign CS4 exporting through Adobe PDF Library 9.0 rather than LiveCycle Designer — a different production pipeline arriving at the same 'JS the non-Adobe fillers won't run' outcome.
77 fields covering both the individual/Self Assessment authorisation (page 1) and the business-tax authorisation (page 2) sections on one combined form, plus signature/date fields on page 3.

Tested request

This exact shape ran against the live API during the recorded test (values here shortened to two fields; the test filled all 76 supported fields). With flatten=true, two identical runs produced byte-identical output — sha256 a1b9fc23a24febe9ad8a9ecb3123a127eb7a1f1282bdfdfe8f019fc1d3b24f1f.

curl -X POST https://pdfops.dev/api/fill-form \
  -F "pdf=@hmrc-64-8.pdf" \
  -F 'fields={"txtName":"PDFops","txtCompanyName":"PDFops"}' \
  -F "flatten=true" \
  -o filled.pdf

Enumerate all 77 field names first with the inspector or POST /api/inspect.

Field schema

All 77 fields (name, type, maxLength, options)

Field name	Type	maxLength
`txtName`	TextField	26
`txtCompanyName`	TextField	40
`AgentName`	TextField	26
`YourAddress1`	TextField	30
`YourAddress2`	TextField	30
`YourAddress3`	TextField	40
`YourPost code`	TextField	20
`YourPhoneNumber`	TextField	30
`AgentsAddress1`	TextField	30
`AgentsAddress2`	TextField	30
`AgentsAddress3`	TextField	40
`AgentsPostCode`	TextField	20
`AgentsPhoneNumber`	TextField	30
`Agent code SA`	TextField	26
`Agent code CT`	TextField	30
`Client ref`	TextField	20
`chkSA`	CheckBox
`chkPartnership`	CheckBox
`SA NI 12`	TextField	2
`SA NI 34`	TextField	2
`SA NI 56`	TextField	2
`SA NI 78`	TextField	2
`SA NI 9`	TextField	1
`UTR 1-5`	TextField	5
`UTR 6-10`	TextField	5
`chkUTR`	CheckBox
`chk to agent`	CheckBox
`chkTrust`	CheckBox
`TR UTR 1-5`	TextField	5
`TR UTR 6-10`	TextField	5
`chkPAYE`	CheckBox
`PAYE NI 12`	TextField	2
`PAYE NI 34`	TextField	2
`PAYE NI 56`	TextField	2
`PAYE NI 78`	TextField	2
`PAYE NI 9`	TextField	1
`Clear form`	Button
`chkCorpTax`	CheckBox
`CRN`	TextField	8
`CT UTR 1-5`	TextField	5
`CT UTR 6-10`	TextField	5
`chkTaxcredits`	CheckBox
`TC NI 12`	TextField	2
`TC NI 34`	TextField	2
`TC NI 56`	TextField	2
`TC NI 78`	TextField	2
`TC NI 9`	TextField	1
`Joint claimants name`	TextField	50
`JC NI 12`	TextField	2
`JC NI 34`	TextField	2
`JC NI 56`	TextField	2
`JC NI 78`	TextField	2
`JC NI 9`	TextField	1
`chkVAT`	CheckBox
`VAT`	TextField	9
`chkVAT not registered`	CheckBox
`chkCIS`	CheckBox
`CIS reference number`	TextField	50
`CIS PAYE Ref no 1-3`	TextField	3
`CIS PAYE Ref no 4-13`	TextField	10
`CIS Agent Gateway ID`	TextField	50
`CIS PAYE ID`	TextField	50
`chkAuthAgentCIS1`	CheckBox
`chkAuthAgent CIS2`	CheckBox
`chkEmp PAYE scheme`	CheckBox
`Emp PAYE Ref no 1-3`	TextField	3
`Emp PAYE Ref no 4-13`	TextField	10
`EMP PAYE Agent Gateway ID`	TextField	50
`EMP PAYE ID`	TextField	50
`EMPchkAuthAgentPAYE`	CheckBox
`EMPchkAuthAgent CIS`	CheckBox
`chkVATDIY`	CheckBox
`VATDIY NI 12`	TextField	2
`VATDIY NI 34`	TextField	2
`VATDIY NI 56`	TextField	2
`VATDIY NI 78`	TextField	2
`VATDIY NI 9`	TextField	1

Frequently asked

Can I fill the HMRC 64-8 programmatically?

Yes — the blank HMRC 05/25 HMRC 64-8 is a fillable AcroForm with 77 fields. In our tested run, all 76 supported fields were filled through the pdfops API and verified by re-inspecting the output; upstream pdf-lib also round-trips it, and pypdf handled its text fields. Field names are listed in the schema on this page.

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