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Self-Assessment Tax Return
Outsourcing for UK Accountancy Practices
software and workflows, helping your practice manage January’s filing pressure with greater confidence.
Get Through January Without Burning Out Your Team
Self Assessment concentrates a year of work into a few weeks. The online filing deadline and the deadline for paying any balancing tax due both fall on 31 January. For clients who are required to make payments on account, the first instalment for the next tax year is also due then. A return filed even one day late can attract an initial £100 penalty, even if no tax is owed.
At Unison Globus, we support UK accountancy practices with Self Assessment tax return preparation from autumn onwards, helping spread the workload across the season rather than leaving it all until January.
Returns prepared in your tax software, ready for your review and approval
Prior-year comparisons to help identify omissions and changes requiring attention
Payments on account calculated, with the amounts explained for inclusion in client communications
Batches delivered to an agreed schedule from October to January
Need Extra Capacity for UK Tax Returns?
Keep tax returns moving through Self Assessment season and beyond. Speak with our team about your practice’s tax preparation requirements and explore how our fixed-price model gives you clear costs, agreed scope and review-ready returns.
✓ Fixed price agreed before work starts
✓ Clear scope and agreed turnaround
✓ Support across UK tax return preparation
✓ 10-hour free trial available
Get in Touch!
Our Self-Assessment Tax Return Services
Self Assessment tax return preparation for individuals and partnerships. For clients preparing for quarterly reporting under Making Tax Digital (MTD) for Income Tax, see MTD for Income Tax. For the underlying financial records, see Digital Bookkeeping.
Individual Tax Returns (SA100)
- Employment income and benefits (SA102)
- Self-employment income and expenses (SA103)
- UK property and rental income (SA105)
- Capital gains (SA108) and foreign income (SA106)
- Savings interest, dividends and pension income
Partnership Tax Returns (SA800)
- Partnership tax return preparation
- Profit allocation between partners
- Partnership statements and supporting information for partners’ individual returns
- Partnership property, foreign income and investment income
Tax Computations and Reliefs
- Capital allowances, including the Annual Investment Allowance
- Pension contribution and Gift Aid relief
- Marriage Allowance and other applicable personal tax reliefs
- Loss relief, including eligible claims to carry losses forward or back
- Student loan repayments and the High Income Child Benefit Charge (HICBC)
Tax Payments and Planning Support
- Balancing payment and payments on account calculations
- Claims to reduce payments on account where appropriate
- Payment schedules for inclusion in client correspondence
- Information on HMRC Time to Pay arrangements for clients who may need them
Tax Season Support
- Agreed return preparation schedules from October
- Lists of outstanding client information
- Weekly progress reporting throughout the busy season
- Support with overdue and catch-up tax returns
Making Tax Digital (MTD) Readiness
- Identifying sole trader and landlord clients who may fall within MTD for Income Tax requirements
- Preparing digital records and workflows for quarterly updates
- Supporting the transition from annual reporting to quarterly updates and year-end tax return submission, where applicable
Key Self Assessment Tax Return Dates
5 October
Deadline to register for Self Assessment if you need to file a tax return for the previous tax year and meet HMRC’s registration criteria.
31 October
Deadline for submitting a paper Self Assessment tax return for the previous tax year. HMRC must receive your return by this date.
31 January
Deadline for submitting your online Self Assessment tax return and paying any tax owed for the previous tax year, including your balancing payment and first payment on account, where applicable. A late return generally incurs an initial £100 penalty.
31 July
Deadline for the second payment on account towards your Self Assessment tax bill, where applicable.
How Unison Globus Supports Your January
With 20+ years of experience, Unison Globus helps your practice spread Self Assessment preparation across the season, reducing reliance on overtime as the January filing deadline approaches.
How We Work with Your Firm
- Dedicated preparers assigned to your Self Assessment client list
- An agreed preparation schedule from October to get work underway early
- Returns prepared within your agreed software workflow, with supporting schedules organised for review
- One consolidated query list per client, issued early enough to allow time for follow-up
- Flexible preparation capacity through December and January
Our Self-Assessment Process
Plan
Agree the client list, workflow schedule and delivery dates before the tax return season begins.
Collect
Use the client’s records and previous year’s tax return, flagging missing information and outstanding queries early.
Prepare
Draft the tax return and tax computation in your software, including the relevant supplementary pages.
Check
Compare the figures with the previous year and complete an internal review checklist before submitting the draft for review.
Deliver
Provide the draft tax return, tax computation, payment summary and outstanding query list for your review and approval.
How Our Delivery Model Works
When you partner with Unison Globus, you gain a structured delivery model designed to support consistent Self Assessment tax return preparation, clear accountability and secure handling of client information.
Structured Workflows and Delivery
- Defined workflows and checklists for each stage of tax return preparation
- Standardised processes to maintain consistency across client files and deliverables
- Work planning aligned with key HMRC deadlines, including 5 October, 31 October, 31 January and 31 July, where applicable
Dedicated Point of Contact
- A single point of contact for communication, coordination and workflow queries
- Access to your team during UK business hours
- Timely updates and query resolution to help keep work moving
Regular Check-ins and Reporting
- Daily or weekly progress updates, depending on your preference
- Return status tracking across your Self Assessment client portfolio
- Progress reporting during the December and January filing period
Quality Assurance and Review
- Defined review stages before work is returned to your practice
- Error tracking and feedback to support continuous improvement
- Workpapers and draft returns prepared in line with your firm's documentation and review standards
Data Security and Compliance
- Information security processes supported by our applicable ISO 27001:2022 and ISO 27701 certifications
- SOC 2 controls and UK GDPR-aligned data processing, subject to the verified scope of our controls and attestations
- Controlled, role-based access and secure data-handling environments
Flexible and Scalable Team Support
- Team capacity adjusted to reflect your practice's workload and requirements
- Additional preparation capacity during the December and January peak
- Consistent workflows and handover processes to support continuity as team capacity changes
Aligned Tools and Working Environment
- Work prepared within your existing tax software environment, including TaxCalc, IRIS, CCH or Capium, where supported
- Workpapers, templates, checklists and documentation aligned with your firm's established processes
Hire Dedicated Self Assessment Tax Return
Preparers in India
Add trained tax return preparers to support your team during the Self Assessment busy season, or retain dedicated capacity year-round for ongoing compliance work.
Flexible Resourcing Models
Full-Time Tax Preparation Support
Ongoing dedicated capacity
- 8 hours per day, aligned with your UK working hours
- Integrated into your existing workflows and review procedures
- Suitable for firms with a consistent, year-round Self Assessment workload
Part-Time Tax Preparation Support
Ongoing dedicated capacity
- Flexible working hours based on your workload
- Suitable for practices that need additional preparation capacity
- Additional support during peak tax periods, subject to availability
Prepaid Block of Hours
Minimum 50 hours · paid upfront · no expiry
- Minimum purchase of 50 hours at £18.50 per hour
- Payment upfront, with no expiry on purchased hours
- Use your hours as required to manage changing workloads
Not sure which model fits? Start with a 10-hour free trial.
Book 10-Hour Free TrialWho Our Services Are For
Practices managing large Self Assessment client portfolios
Firms relying on overtime to meet the January filing deadline
Practices serving landlords and sole traders
Firms preparing clients for Making Tax Digital (MTD) for Income Tax
Software Landscape
Explore Our Other Services
As your practice grows, your requirements often go beyond this service. Unison Globus supports UK firms across additional areas to ensure continuity and control.
MTD for Income Tax
Quarterly digital updates and year-end returns for sole traders and landlords.
Tax Preparation
The full range of personal, business and corporate tax compliance.
Company Tax Returns
CT600 preparation with computations and iXBRL accounts.
Digital Bookkeeping
Cloud-based, MTD-compliant bookkeeping and cleanup work.
Year-End Accounts
FRS 102 / FRS 105 statutory accounts with iXBRL filing.
Looking for something specific?
Explore All ServicesFAQs
Register by 5 October where required, file a paper return by 31 October, and file online and pay by 31 January. The second payment on account is due by 31 July, where applicable.
There is an automatic £100 penalty for late filing, even if no tax is due. Further penalties may apply if the return remains outstanding, and interest may apply to late tax payments.
They are normally based on the previous year’s relevant tax liability and paid in two instalments, on 31 January and 31 July. We calculate them and prepare a payment schedule for your client letter.
From October. Starting early spreads the workload and leaves time to chase missing records before the deadline.
We prepare returns for your review and approval. Submission arrangements are agreed with your practice.
Yes, including property portfolios, jointly owned properties and holiday-let income under the current tax rules.
Your software, including TaxCalc, IRIS, CCH and Capium.
Yes, we offer a 10-hour free trial so you can assess our team’s work before committing.
Get Your Self-Assessment Tax Returns Filed Accurately & On Time
Agree a batch schedule now and spread the work from October, instead of compressing it into January.
- Share your client volumes
- Agree a batch schedule
- Start with a 10-hour free trial
