Help centre
Walkthroughs and reference for every scheme, plus answers to the questions our customers ask most.
Getting Started
Getting started with OneSixth
Connect your first accounting platform, add a firm, and run your first calculation.
Accountant portfolio — managing multiple clients
The cross-client dashboard for practices: every client firm, organisation counts, subscription status and overdue-period alerts.
Training sandbox — practise any scheme safely
Create dummy organisations seeded with realistic data to learn each VAT scheme. Nothing is posted to a real accounting platform.
Connections
Connecting Xero, QuickBooks, Sage and FreeAgent
OAuth, scopes, multi-org connections, and what OneSixth does and doesn't read from your accounting data.
HMRC Making Tax Digital (coming soon)
A planned direct HMRC MTD connection: stagger detection from live VAT obligations, filing reconciliation, and a VAT deadline calendar.
Schemes
TOMS — Tour Operators' Margin Scheme
Quarterly provisional calculations, deferrals, the year-end annual adjustment, and the full audit trail.
Motor Trade — second-hand vehicle margin scheme
Per-vehicle margin VAT for car dealers, with the stock book HMRC requires, DVLA lookups and bulk import.
Global Accounting scheme
Bulk margin VAT for high-volume, low-value second-hand goods.
Horses & Ponies scheme
Specialised margin scheme for the equine trade.
Second-Hand Goods margin scheme
The standard per-item margin scheme for antiques, works of art, collectors' items, and general second-hand goods.
Partial Exemption
Setup wizard, tax-code mapping, transaction classification, the standard method, de minimis, the annual adjustment and SMO.
Billing & plans
Plans and pricing — Practice, Business, and Charity
How OneSixth pricing works: graduated per-organisation tiers for practices, fixed monthly tiers for businesses by entity count, and a 25% charity discount that applies to either plan.
Trials and welcome offers — what you get for free
Business gets a 30-day full-product trial with no card needed. Practices get a 90-day welcome offer where the first organisation is free. Here's how each works and what happens at expiry.
Charity discount — claiming 25% off as a registered charity
Registered charities get 25% off either OneSixth plan (Practice or Business). We accept Charity Commission, OSCR and CCNI registration numbers, and HMRC CASC clubs by name. The discount is retroactive from when you provide your details.
Adding and removing organisations — how billing changes
Pro-rata charges when you add an organisation mid-cycle, automatic credit when you remove one, and how graduated tiers recompute.
Switching plans and changing billing
Move between Practice and Business, change the billing contact email, hand over an organisation to or from a practice, or transfer between practices.
Cancelling your subscription and data retention
How to cancel, the 7-day export window, paid retention options for the HMRC six-year requirement, and what gets deleted when.
What happens if a payment fails
The dunning retry schedule, when an account moves to read-only, and how to recover after a failed payment.
Practice or Business plan — choosing the right one
How the Practice and Business plans differ, what we monitor for plan-fit issues, and how to switch if you've picked the wrong one.
Subscription status — what each banner means
Plain-English explanation of the trial, payment-issue, and cancelled / retention banners you may see at the top of OneSixth, and what to do about each one.