Why is there a £85,000 limit on self-employment or property earnings?

untied does not currently support self-employment or property earnings above £85,000 per income source.

There is no limit on other sources - such as employment/salary, or investment income.

The reason for this is that above this level you are likely to need to be VAT-registered and be required to produce accounts in more detail than untied generates by default. While in theory you could use untied for the aggregation, you may find that there are other software products that better support you for now.