Previously you had around nine months to pay tax from the previous full financial year to February (less if not filing online).
Now you have to pay half of the current year's bill this January and the estimated balance in June.
Essentially, this means that everyone who is self-assessed and largely self-employed will see a doubling of their tax for the current financial year.
I dread to think of the consequences this will have on the entrepreneurial community and is yet another crass example of how politicians say they want one thing and enact legislation that works in absolutely the other direction. When will they learn ?