The tax choice could potentially be implemented using tax returns.

When filing their tax returns, taxpayers could be given an option to allocate a certain percentage of their tax payment to various sectors, programs, or projects. The specifics of this could vary widely, depending on the details of the system designed by the government.

However, implementing this kind of system would have significant challenges. It would require substantial changes to tax forms, procedures, techniques, and new laws or regulations. Additionally, checks and balances would need to be checks and balances in place to ensure that all necessary government functions receive sufficient funding, even if they're not as popular or well-known among taxpayers.

Also, there would be logistical considerations about what happens if the taxpayer doesn't allocate their taxes or if their allocations don't add up to 100%. There might be default allocations and systems to handle incomplete or incorrect allocations.

It's essential to make the system flexible enough to cater to those who wish to participate actively while also accommodating those who prefer not to or don't have the time or resources to make informed choices about tax allocation. Public education about the importance and impact of tax allocation would also be an essential part of this system.

Here's a broad illustration of how it might work:

Listing of Choices: The government could provide a list of categories for which tax money can be earmarked on the tax return form. These categories could be broad (e.g., education, healthcare, defence) or more specific (e.g., public school funding, renewable energy research).

Allocation of Funds: Each taxpayer could then specify what percentage of their tax payment they would like to allocate to each category. For example, a taxpayer might give 30% of their taxes to healthcare, 20% to education, etc.

Processing and Allocation: After the tax returns are processed, the government distributes the tax funds as each taxpayer directs, ensuring that the allocated money reaches the specified sectors or programs.

Default Allocation: If taxpayers do not specify their preferences, their tax dollars could be allocated according to a default budget plan. The government could determine this plan based on factors such as historical budget proportions, current needs, or a combination of both.

Proportional Allocation: Another option could be to distribute the unallocated tax dollars proportionally based on the preferences of those participating. This way, the tax dollars of non-participants still go toward areas that their fellow citizens value.

Government Discretion: The government could also reserve the right to allocate the unassigned tax dollars at their discretion, focusing on areas of critical need.