The Picket Line offers many interesting suggestions to organize mutual aid for tax resisters. They are:
1. Tax resister insurance.
2. Communes, collectives and co-housing projects.
3. Supporting resisters as an employer. (unfortunately I guess this option is not available to Anarchists)
4. Disrupting auctions of seized property.
5. Pay cash so as not to leave a paper trail.
6. Use barter to avoid taxable transactions.
7. Manufacture and sell goods as alternatives to taxed products.
8. Buycotts and boycotts that favor resisting businesses.
9. Social boycotts/shunning/noncooperation with tax collectors.
10. Violently resisting tax collectors, disrupt trials/auctions, intimidate collaborators.
11. Boycotts/social boycotts of non-resisters.
12. Maintain solidarity in the face of divide-and-conquer tactics.
13. Keep a record of the “sufferings” of resisters.
14. Sign petitions and public advertisements, engage in public protests.
15. Hold resisters’ property as an informal trustee.
16. Keep in contact with resisters and express support.
17. Form groups for mutual support and coordinated decision-making.
18. Give financial aid to evicted rent strikers.
19. Comfort and aid imprisoned resisters.
20. Support the families of imprisoned resisters.
21. Study the law, give legal support.
22. Combine redirected taxes for dramatic charity give-aways.
The Prime Directive 
A particularly interesting one is the idea of disrupting auctions of seized property. It would be an interesting tactic for those support the tax resistances to group together in order to by back the seized property and return it to its original owner. It’s like a total counter economic, horizontally-organised, insurance company.
Good for you! In the world of the emergent Orwellian corporate state, the bad news is that it is damned difficult to avoid the reach of the State and Its Own. The good news is that there is power in numbers. If enough people physically ( / financially) band together, then ultimately no state will be able to hold them down. (Just ask Marie Antoinette.)