RentalBux vs. "untied"
Which MTD Software Is Better for UK Landlords and Sole Traders?
Overall Winner: RentalBux
RentalBux is the more complete platform for landlords who need both MTD compliance and property management in a single subscription. It combines full Making Tax Digital compliance across UK property income, foreign property income, and self-employment income with comprehensive property management tools — tenant management, rent tracking, HMO support, joint ownership profit-splitting, automated bank feeds, AI-driven expense categorisation, and a free plan for single-property landlords until March 2028. "untied" is a powerful, award-winning personal tax and MTD platform operated by UT Tax Ltd — the first end-to-end app recognised by HMRC for Making Tax Digital for Income Tax. It supports all three MTD income types including foreign property, covers quarterly updates and the full annual tax return, includes built-in AI, real-time tax calculations, automatic mileage tracking, unlimited bank connections, and handles a uniquely wide range of income sources including capital gains, CIS, non-residency, and foreign income. However, "untied" is a tax-first platform, not a property management tool. It does not offer tenant management, rent tracking, property compliance alerts, HMO support, or invoicing for landlords. The right choice between these two platforms therefore depends entirely on what you need: full tax compliance with an unmatched breadth of income source coverage, or combined property management and MTD accounting in one place.
At-a-Glance MTD Software Comparison
Key differences between RentalBux and "untied" across MTD compliance, property management, bookkeeping, pricing, and landlord-specific features.
| Feature | RentalBux | "untied" |
|---|---|---|
| Software Type | Property/Landlord Platform | Personal Tax & MTD App |
| Target Users | Landlords, Sole Traders, Letting Agents | Sole Traders, Landlords, Freelancers, High-Earners, Accountants |
| Income Sources Supported | Sole Trader + UK Property + Foreign Property | Sole Trader + UK Property + Foreign Property |
| Free MTD Software Plan | Free until March 2028 (1 property) | 30-day free trial |
| MTD Quarterly Updates to HMRC | Yes | Yes |
| Final Declaration | Yes | Yes |
| Bank Reconciliation | Yes | Yes |
| Automated Bank Feeds | Yes | Yes |
| Invoice Creation | Yes | Yes |
| Receipt Capture (OCR) | Yes | Yes |
| Expense Auto-Categorisation | Coming soon | Yes |
| Property Portfolio Management | Yes | No |
| Tenant Management | Yes | No |
| Joint Ownership & Profit Sharing | Yes | Yes |
| Payroll | No | No |
| HMO Unit-Level Tracking | Yes | No |
| HMRC SA105 Box Pre-Mapping | Yes | Yes |
| Spreadsheet Import/Export | Yes | Yes |
| Platform | Web, iOS, Android | Web, iOS, Android |
| GDPR Compliant | Yes | Yes |
What Is RentalBux? What Is "untied"?
What Is RentalBux?
All-in-One MTD Software for Landlords and Sole Traders
RentalBux is an all-in-one property management, accounting, and Making Tax Digital compliance platform built specifically for UK landlords, letting agents, and self-employed individuals. Designed with direct input from accountants who specialise in property and sole trader tax, RentalBux covers everything from tenancy management and rent collection to full bookkeeping with a pre-configured chart of accounts tailored to the property sector.
RentalBux is fully HMRC-recognised for Making Tax Digital for Income Tax across all three qualifying income categories: UK property income, foreign property income, and self-employment. This makes it one of the only landlord-specific MTD software platforms that can handle a landlord who also runs a sole trader business, all from a single subscription.
A major differentiator is RentalBux's pricing model: single-property landlords can use the platform completely free until March 2028, making it one of the most affordable HMRC-approved MTD software options for landlords entering the MTD regime.
What Is "untied"?
"untied" is the UK's personal tax app, operated by UT Tax Ltd and launched in 2018. It was the first end-to-end app to be recognised by HMRC for Making Tax Digital for Income Tax — a landmark confirmed on untied's accountants page and widely noted in the MTD software market. The platform is HMRC-recognised, regulated by the FCA (FRN 910169) as a registered account information services provider, and supervised by the Chartered Institute of Taxation.
"untied" is built around a single founding principle: make UK personal tax as simple as possible for the people who find it most daunting — sole traders, freelancers, landlords, gig workers, and high-earners. It connects to unlimited bank accounts (the majority of UK banks supported), automatically tracks and categorises transactions using rules and built-in AI, logs mileage automatically or manually, generates invoices, calculates tax in real time, and files directly to HMRC — including both quarterly MTD updates and the full end-of-year tax return.
Strengths
- Free MTD software for single-property landlords until March 2028
- Handles sole trader + UK property + foreign property income in one platform
- Joint ownership with automatic profit-sharing split by ownership percentage
- Pre-built chart of accounts tailored for landlords and sole traders
- AI-powered expense auto-categorisation and OCR receipt capture
- Agent filing on behalf of landlords — ideal for accountants and letting agents
- Supports HMO properties with auto-created units
Strengths
- First end-to-end app HMRC-recognised for MTD — a proven track record
- Covers MTD quarterly updates and the full annual tax return in one app
- Widest income source coverage of any personal tax app — capital gains, CIS, foreign income, non-residency, multiple PAYE, EIS/SEIS
- Built-in AI insights and real-time tax calculations
- Automatic and manual mileage tracking — useful for landlords who travel between properties
- Can be used as full record-keeping software or as bridging software
- FCA-regulated and supervised by the Chartered Institute of Taxation
- Accountant/adviser access on Pro plan with real-time collaboration
- 4.8 stars on Trustpilot (37 reviews); consistently praised for ease of use and customer support
Limitations
- Newer to market compared to established platforms
- No yield or LTV investment analysis tools
- No MTD for VAT support yet
- Some advanced reporting features still in development
- Limited third-party app integrations
- No offline capability
- No tax liability forecasting feature currently
Limitations
- No property management features: no tenant management, rent tracking, HMO tools, or compliance alerts
- No free permanent plan — 30-day trial only; paid plan required for filing
- Not designed for letting agents managing multiple landlord client portfolios at scale
- No dedicated property portfolio dashboard
- Chart of accounts, journal entries, and formal P&L not confirmed
- Pricing is annual subscription (no confirmed free ongoing plan)
- Property income capped at £90k on Lite plan (unlimited on Pro if in MTD)
- Adviser access subject to adviser onboarding at untied's discretion
- Smaller review base compared to more established platforms
Making Tax Digital Compliance
How RentalBux Handles MTD Compliance
RentalBux supports all three MTD-qualifying income categories: sole trader income, UK property income, and foreign property income. This makes it suitable for landlords who also earn self-employment income, eliminating the need for separate software. Most accounts are pre-mapped to HMRC Self-Assessment boxes. RentalBux also supports agent filing, allowing accountants or letting agents to submit MTD returns on behalf of their landlord clients.
How "untied" Handles MTD for Landlords and Sole Traders
"untied" was the first end-to-end app recognised by HMRC for MTD for Income Tax — a distinction confirmed on the platform's own accountants page. The platform supports all three MTD income types: sole trader income, UK property income, and foreign property income. It covers both the quarterly updates required throughout the year and the full end-of-year final declaration (tax return), all submitted directly to HMRC from within the app.
| Feature | RentalBux | "untied" |
|---|---|---|
| HMRC Recognised (MTD ITSA) | Yes | Yes |
| MTD Quarterly Updates | Yes | Yes |
| Final Declaration | Yes | Yes |
| Digital Record Keeping | Yes | Yes |
| Digital Links Compliant | Yes | Yes |
| Sole Trader Income | Yes | Yes |
| UK Property Income | Yes | Yes |
| Foreign Property Income | Yes | Yes |
| Multiple Income Streams | Yes | Yes |
| Agent Filing on Behalf | Yes | Yes |
Winner: Tie — depends on priorities — RentalBux wins on property management integration, free plan access, and confirmed agent filing at scale. "untied" wins on breadth of MTD income source and tax situation coverage, final declaration depth, and being the first HMRC-recognised end-to-end MTD app. For landlords with complex personal tax situations beyond property and self-employment, "untied" is the more complete compliance tool.
Property Management
RentalBux: Property Management
RentalBux provides comprehensive property portfolio management with tenant management, rent tracking, property expense allocation, and support for multiple properties. A standout feature is its joint ownership and profit-sharing capability: landlords can define ownership percentages once, and RentalBux automatically splits rental income and expenses. RentalBux also supports HMO properties, automatically creating individual units.
"untied": Tax Platform Only — No Property Management Features
"untied" does not include property management tools. It is a personal tax and MTD platform focused on recording income and expenses, calculating tax, and filing to HMRC. Tenant management, rent tracking, compliance certificate reminders, HMO unit management, and tenancy document generation are not part of the "untied" product. Landlords who also need property management workflows will need a separate platform alongside "untied".
| Feature | RentalBux | "untied" |
|---|---|---|
| Property Portfolio Management | Yes | No |
| Tenant Management | Yes | No |
| Rent Tracking | Yes | No |
| Property Expense Allocation | Yes | Yes |
| Multiple Property Support | Yes | Yes |
| HMO Property Support | Yes (auto-creates units) | No |
| Joint Ownership/Profit Sharing | Yes (auto-split by %) | Yes |
| Maintenance Tracking | No | No |
| Tenant Screening | No | No |
| Compliance Document Alerts | Yes | No |
| Arrears Tracking | No | No |
Winner: RentalBux — clear — RentalBux provides a comprehensive, confirmed property management feature set. "untied" is a tax-filing platform and does not include any property management tools. Landlords who need more than MTD compliance must use a separate platform alongside "untied".
Bookkeeping, Accounting & Digital Record Keeping
RentalBux: Structured Accounting
RentalBux includes a pre-built chart of accounts specifically designed for landlords and sole traders, covering rental income, insurance, property repairs, professional services, utilities, and tenant deposits. All accounts are pre-mapped to HMRC Self-Assessment boxes. The platform supports cash basis accounting, bank reconciliation, and journal entries.
"untied": AI-Powered Transaction Tracking with Unlimited Bank Connections
"untied" connects to unlimited bank accounts (the majority of UK banks supported), automatically imports transactions, and allows users to categorise them using rules, AI, or manually. The platform supports automatic or manual data entry, CSV import and export, and real-time tax calculations based on transactions recorded. Users can set rules so that the app automatically learns and categorises recurring transactions over time.
| Feature | RentalBux | "untied" |
|---|---|---|
| Cash Basis Accounting | Yes | Yes |
| Chart of Accounts (Pre-built, Landlord-Tailored) | Yes | No |
| Journal Entries | Yes | No |
| Bank Reconciliation | Yes | Yes |
| Automated Bank Feeds | Yes (Major UK banks) | Yes |
| Open Banking Integration | Yes | Yes |
| Double-Entry Bookkeeping | Yes | No |
| HMRC Box Pre-Mapping | Yes | Yes |
| Xero Integration | No | No |
| Spreadsheet Import/Export | Yes | Yes |
| Digital Record Storage | Yes | Yes |
Winner: RentalBux leads on accounting structure: chart of accounts, journal entries, and double-entry bookkeeping for landlords who need audit-ready records.
Invoicing, Expense Tracking
RentalBux: Expense Management
RentalBux includes OCR receipt capture, structured expense tracking with landlord-specific categories, auto-categorisation, invoice creation with customisable branding, and payment tracking with reminders.
"untied": AI Insights, Rule-Based Automation, and Invoicing
"untied" includes built-in "untied AI" — confirmed on the platform homepage — which provides insights and tax optimisation suggestions based on a user's transaction data. Users can set rules to automate income and expense tagging, and the AI learns from these over time. "untied" also supports invoice creation and payment requests, allowing sole traders and landlords to send invoices and chase payments directly from the app. Photo evidence can be uploaded against transactions. Automatic mileage tracking is a confirmed differentiating feature — particularly useful for landlords who travel between properties and wish to claim vehicle expenses.
| Feature | RentalBux | "untied" |
|---|---|---|
| Invoice Creation & Sending | Yes | Yes |
| Invoice Customisation/Branding | Yes | No |
| Online Payment Collection | Yes | Yes |
| Payment Tracking/Reminders | Yes | Yes |
| Expense Tracking | Yes | Yes |
| Receipt Capture (OCR/Photo) | Yes | Yes |
| Expense Categorisation | Yes | Yes |
| Automated Transaction Matching | Yes | Yes |
| Mileage Tracking | No | Yes |
| AI Auto-Categorisation | Coming soon | Yes |
Winner: RentalBux wins on AI-powered OCR receipt capture and branded invoice creation tailored for landlords. It offers strong automation features suited to it's audiences.
Reporting & Tax Forecasting
RentalBux: Formal Accounting Reports
RentalBux produces structured financial reports including profit & loss statements, balance sheets, journal reports, ledger reports, and trial balances. Smart categorisation helps ensure accuracy.
"untied": Real-Time Tax Calculation and AI-Driven Insights
"untied"'s reporting centres on real-time personal tax calculation — as transactions are added throughout the year, the platform continuously updates the user's estimated tax liability. "untied AI" generates insights that identify potential tax savings and flag items for review. The platform also highlights tax reliefs the user may be entitled to and optimises these automatically where allowed.
| Feature | RentalBux | "untied" |
|---|---|---|
| Profit & Loss Report | Yes (formal) | No |
| Balance Sheet | Yes | No |
| Trial Balance | Yes | No |
| Dashboard/Overview | Yes | Yes |
| Real-Time Financial Data | Yes | Yes |
| Cash Flow Reporting | No | No |
| Tax Estimate/Forecast | No | Yes |
| AI-Powered Features | Coming soon | Yes |
Winner: RentalBux leads on formal accounting reports. It provides Profit and Loss report, balance sheet, trial balance.
Collaboration & Mobile Apps
RentalBux's Collaborative Features
RentalBux enables agent filing, which gives accountants and letting agents the ability to submit directly on a landlord's behalf. It also offers a dedicated iOS as well as an Android app.
"untied": Collaborative Features
"untied" provides adviser access on its Pro plan, confirmed on the accountants page. Advisers and their clients see the same view within the platform, enabling real-time collaboration. "untied" estimates advisers can generate an increase of £200 per client per year from real-time support, while saving £200 a year in administration. Adviser access is subject to adviser onboarding at untied's discretion, and is restricted to supporting fully paid year-round untied Pro users. "untied" also provides dedicated iOS and Android mobile apps alongside full web browser access — allowing both landlords and their advisers to manage tax from any device.
| Feature | RentalBux | "untied" |
|---|---|---|
| Accountant/Advisor Portal | Yes | Yes |
| Multi-User Access | Yes | Yes |
| Agent Filing on Behalf | Yes | Yes |
| Bank Integration | Yes | Yes |
| Platform | iOS, Android | Web, iOS, Android |
| Web Browser Access | Yes | Yes |
| FCA Regulated | Yes | Yes |
| GDPR Compliant | Yes | Yes |
Winner: RentalBux - RentalBux has a slight edge for letting agencies managing large portfolios due to its confirmed multi-landlord agent filing at scale. It also offers confirmed iOS and Android apps, web browser access, adviser access, and direct HMRC filing.
Ease of Use, Support & Security
RentalBux: Guided Workflows
RentalBux uses guided workflows, clear dashboards, and no accounting jargon. The platform offers phone support, email/chat support, and a help centre with guides and knowledge base articles.
"untied": Ease of Use
"untied" has built its reputation on simplicity and outstanding customer support. Users on Trustpilot (4.8 stars, 37 reviews) and reviews.co.uk (197 reviews) consistently describe the platform as intuitive, stress-free, and backed by a responsive team — with the CEO (Kevin) personally engaging with user queries in webinars and email support. The platform has been used to file the UK's first fully mobile tax return and was the first to offer integrated payments directly to HMRC, establishing a track record of innovation since its 2018 launch. "untied" is Techstars-backed and recognised by FinTech London. Support is available via email, help centre, and group introduction calls, with one-to-one calls available for paid plan users.
| Feature | RentalBux | "untied" |
|---|---|---|
| Phone Support | Yes | No |
| Chat Support | Yes | Yes |
| Email Support | Yes | Yes |
| Help Centre/Knowledge Base | Yes | Yes |
| FCA Regulated | Yes | Yes |
| Enterprise-Grade Security | Yes | Yes |
RentalBux Features
Sole Trader Income Support for MTD
RentalBux is one of the few landlord-focused MTD software platforms that supports self-employment income alongside UK and foreign property income within a single account. Landlords who also run a trade, consultancy, or freelance business can manage all quarterly submissions from one dashboard.
Custom Chart of Accounts for Landlords
A property-tailored chart of accounts covering rental income, mortgage interest, insurance, repairs, utilities, letting agent fees, and more — all pre-mapped to HMRC Self-Assessment boxes. No setup required; the system is ready to use from day one.
Agent Filing on Behalf of Landlords
Letting agents and accountants can submit MTD quarterly updates and the Final Declaration on behalf of landlord clients directly from the platform.
Branded Invoice Creation
Invoice creation with customisable branding for service charges and commercial landlords.
AI-Powered OCR Receipt Capture with Auto-Categorisation (Coming soon)
RentalBux's AI will read uploaded receipts and categorise the expense automatically against the pre-built chart of accounts.
Formal Accounting Reports
Balance sheet, trial balance, ledger reports, and journal reports.
Free Plan Including MTD Submissions Until March 2028
RentalBux's free single-property plan includes MTD quarterly submissions until March 2028.
Unique Features Only "untied" Offers
First End-to-End App HMRC-Recognised for MTD for Income Tax
"untied" was the first end-to-end personal tax app to achieve HMRC recognition for Making Tax Digital for Income Tax — confirmed on the platform's own accountants page and widely noted across the MTD software market.
Capital Gains Support (SA108 — Including Crypto)
"untied" supports capital gains tax on all plans, including cryptocurrency disposals. Landlords who have sold a property, shares, or crypto assets can file their complete tax position from a single platform.
Non-Residency and Non-Domicile Support (SA109)
"untied" supports non-UK residents and non-domiciles, including the remittance basis. This is particularly valuable for overseas landlords with UK property income who are not UK residents.
CIS (Construction Industry Scheme) Support
Sole traders working in the construction industry who are also landlords can manage their CIS income and property income from a single "untied" subscription.
Automatic and Manual Mileage Tracking
"untied" logs car and bike mileage automatically or manually, calculating vehicle expense claims in real time. Useful for landlords who travel between properties for management or maintenance purposes.
Pay HMRC Directly from the App
"untied" allows users to pay HMRC directly from within the platform — a confirmed differentiating feature that simplifies the full cycle from record keeping to payment.
Bridging Software Mode
"untied" can be used purely as bridging software for users who prefer to maintain records in spreadsheets, connecting existing records to HMRC's MTD gateway for submission.
Supervised by the Chartered Institute of Taxation
In addition to FCA regulation, "untied" is supervised by the Chartered Institute of Taxation — providing an additional layer of professional oversight for a personal tax platform.
Who Should Choose RentalBux?
RentalBux is a strong fit if you:
Landlords with Mixed Income Streams
If you earn from both property and self-employment, RentalBux handles sole trader income alongside UK and foreign property income in a single MTD-compliant platform.
Joint Owners and Family Portfolios
The automated profit-sharing split is a standout feature. Define ownership percentages once and RentalBux calculates each owner's share automatically.
Budget-Conscious Landlords Entering MTD
Free MTD software for single-property landlords until March 2028, with no upfront commitment.
Landlords Who Want Proper Accounting Structure
Chart of accounts, journal entries, profit & loss, balance sheet, and trial balance give RentalBux a structured accounting foundation.
Accountants and Letting Agents
Agent filing on behalf, multi-user access, and spreadsheet import make RentalBux practical for professionals managing multiple landlord portfolios.
Commercial Landlords and HMO Owners
Invoice creation with branding for service charges, plus automatic HMO unit creation and tenant management.
Who Should Choose "untied"?
"untied" is a good choice for:
Landlords with Complex Personal Tax Situations
"untied" is the strongest choice for landlords who also have capital gains (including property disposals or crypto), foreign income, non-resident status, CIS income, multiple PAYE employments, or EIS/SEIS investments — all handled within a single annual subscription.
Sole Traders Who Are Also Landlords
"untied" supports both income streams comprehensively, including all their associated self-assessment supplementary forms, making it ideal for the growing number of people with mixed self-employment and rental income.
Landlords Who Travel Between Properties
Automatic mileage tracking makes "untied" particularly practical for landlords who manage properties in person and want to claim vehicle expenses without a separate mileage app.
Non-Resident Landlords
"untied"'s confirmed support for non-residency (SA109) and the remittance basis makes it one of the few personal tax apps that can handle the complete tax position of a non-UK resident landlord with UK property income.
Landlords Who Want the Simplest Possible App
"untied" has been consistently praised for ease of use and accessibility, even by users who are self-described technophobes. If the priority is a simple, mobile-first experience that files your complete tax return without an accountant, "untied" is a strong option.
Landlords Who Prefer Bridging Software
If you already keep detailed records in Excel or another system and simply want a compliant route to MTD quarterly submissions, "untied"'s bridging software mode allows this at a lower ongoing overhead.
Landlords Using an Accountant Who Wants Real-Time Access
"untied"'s adviser access allows real-time collaboration — the accountant sees the same view as the client, reducing errors and reducing year-end administration.
Shreya Bhattarai
Shreya Bhattarai is a digital marketer specialising in content strategy, digital advertising, and website development. She focuses on enhancing brand visibility, engaging target audiences, and delivering data-driven marketing solutions.