Small business rate relief on property portfolio

[xenium]

hi,
I am in the process of moving some rental properties from council tax to business rates, due to the tax rules on short lets (self catering holiday lets)

The first property has been moved, with rateable value of £2100 (as of next year), and this has been deemed exempt by VOA as it falls below the £6000 threshold for 100% relief.

Suppose I were to move more properties onto short lets, and consequently onto business rates, the rules seem to imply that for tax efficiency 3 properties is the optimal number, see google spreadsheet example here: tinyurl.com/hm3zryf

Is my calculation correct, eg for 4 properties on business rates, the rate relief would be (£12,000 - £ 8,400) / (£12,000 - £ 6,000) = 60% and this is applied to the total bill?

Clearly the threshold rules can change at any time, and there are many other factors to consider too, but I just wanted to check here if I have understood the calculation method correctly.

Many thanks