Bridging software is a category of tool that connects a taxpayer's existing bookkeeping records, typically a spreadsheet or basic accounting package, to HMRC's MTD systems, allowing the required digital submissions to be made without switching to a fully integrated MTD-native platform.
Under Making Tax Digital for Income Tax, submissions must flow digitally from the source record to HMRC with no manual re-keying at any link in the chain. HMRC's rules allow the use of software that "bridges" between a taxpayer's own records and the HMRC API, provided the link between them is digital (a formula-driven connection, not a copy-paste).
For CIS sole-trader subcontractors who already use spreadsheets to track invoices and materials, bridging software can be a lower-cost route into MTD ITSA compliance than replacing their entire bookkeeping system. Typical bridging tools import the quarterly income and expenses totals from the spreadsheet and transmit them to HMRC in the correct MTD format.
Practical considerations:
- Digital link requirement. The connection between the spreadsheet and the bridging tool must be digital throughout. Typing figures manually from a spreadsheet into a separate submission tool does not meet the digital-link rule.
- Quarterly update deadlines apply regardless of software type. Bridging software does not extend the 7 August, 7 November, 7 February and 7 May deadlines.
- HMRC-recognised software list. Only software that appears on HMRC's recognised software register can be used for MTD submissions. Check the HMRC website before committing to any tool.
- CIS gross-income entries. Whichever software you use, the income figure entered must be gross CIS income before deductions, not the net receipts in your bank account.
Whether bridging software or a fully integrated platform is more suitable depends on the volume and complexity of a subcontractor's records. A CIS accountant can advise on the right approach for your situation. For the full MTD ITSA context see our guide on Making Tax Digital and CIS.