Write the plain-English explainer
People search questions first: does this apply to me, what do I have to do, what software do I need. A clear page on your site answering those, in plain language, is what brings them to you. Link to HMRC’s guidance for the details that may change, and keep your own page focused on what it means for them.
Say who you help
Sole traders and landlords are the people affected, so name them. A page for landlords and a page for sole traders will match their searches better than a general "tax services" page.
Add it to your Google Business Profile
List Making Tax Digital support as a service and post about it, especially ahead of quarterly deadlines. A short post explaining one common question is enough.
Time your content around deadlines
Searches spike before deadlines: the January self-assessment deadline, and now the quarterly updates. Publish and post a few weeks ahead, when people start to worry. On the day itself is too late.
Ask the right clients for reviews
Reviews from sole traders and landlords you’ve helped through the change tell the next person you understand their situation.
For the rest of what decides accountant searches, see the local SEO guide for accountants. The free audit will show how your profile looks today.
The thing that compounds in local SEO is the boring work of getting the fundamentals right, and keeping them right, month after month.