Self Assessment
Submitting a Self Assessment quarterly update
Digital income and expense records from the ledger for sole traders and partners.
Self Assessment in Hydra is for sole traders and partnerships — limited companies use the Corporation Tax rail instead.
Pick the tax year and period dates. Hydra totals turnover and expenses from books in that window, validates the payload, then submits with fraud-prevention headers.
If the tax calculation looks higher than expected, check allowances (for example dividend nil-rate bands still consume basic-rate band) before amending figures.