Hydra Support
Answers for every head of the practice
Search guides for CT600, MTD VAT, Self Assessment, payroll, and HMRC connection issues — written for accountants using HydraTax.
Browse by topic
Getting started
Open a practice, add clients, and take your first filing from draft to HMRC.
2 articles →
Troubleshooting
Decode gateway rejections, pending states, and “why didn’t this land?†moments.
3 articles →
Corporation Tax
CT600 periods, credentials, amendments, and what to expect after submit.
3 articles →
MTD VAT
Obligations, box drafts from books, reconnecting MTD, and repayment returns.
3 articles →
Self Assessment
Quarterly updates, digital records, and reading the tax calculation.
2 articles →
PAYE & RTI
Employees, payday FPS, EPS when nothing is paid, and employer refs.
2 articles →
HMRC connection
OAuth links, expired tokens, fraud-prevention headers, and test vs live.
2 articles →
Practice desk
Multi-client workflows, deadlines, audit trail, and team roles.
2 articles →
Popular right now
Your first week on the Hydra desk
How to create a practice workspace, seed clients, connect HMRC, and complete a guided filing.
Adding clients to your practice
Limited companies, sole traders, and employers — which identifiers Hydra needs before you can file.
Fixing common CT600 submission errors
Authentication failures, invalid UTR, period conflicts, and business-logic rejections explained in plain language.
Why a filing shows as pending with HMRC
What “pending†means after submit, how long to wait, and when to open a support ticket.
CT600 filing checklist
What to gather before you open the Corporation Tax rail — periods, P&L, balance sheet, and prior filings.
Drafting an MTD VAT return from books
How Hydra maps income and expense lines into the nine boxes, then guides review and submit.
Submitting a Self Assessment quarterly update
Digital income and expense records from the ledger for sole traders and partners.
Running payroll and submitting FPS on payday
Employees, monthly pay calculation, and Full Payment Submission from the client employer workspace.
Fraud-prevention headers — why submit can be blocked
Hydra refuses to call MTD APIs when browser metadata is incomplete.
How to contact Hydra support
What to include so we can resolve gateway and practice issues quickly.
Still stuck?
Send the client name, filing type, period, and correlation ID from the audit trail — Hydra support can move faster with those details.