Frequently asked questions How will I know if my tax affairs are being investigated? The Inland Revenue must inform you in writing if you are being investigated. They will also put their findings in writing telling you exactly what they found. Can I estimate my income if I don't have all the information in my tax return? Can I complete my return after the January 31st deadline? I think I paid too much tax, how do I get it back? © Taxes. All rights reserved.