tk.cpa Extension Guide

The most complete reference on US tax filing extensions

Federal, all 50 states plus DC, city and local taxes, and every entity and tax type - individuals, businesses, partnerships, estates and trusts, nonprofits, information returns, estate tax, and excise.

An extension to file is not an extension to pay tax.

An extension moves the filing deadline. It does not move the payment deadline. The tax is still due by the original due date in every jurisdiction that imposes one, and interest and failure-to-pay penalties accrue on any unpaid balance even under a fully valid extension.

Where do you start?

I am an individualForm 4868, automatic 6 months, IRC §6081 I am a businessForm 7004 - corporations, S corps, partnerships I handle an estate or trustForm 706 / Form 4768, plus state estate & inheritance tax extensions I run a nonprofitForm 8868, Form 990 series I sponsor a benefit planForm 5558, Form 5500 series I have foreign assets, trusts, or entitiesForms 3520, 3520-A, 5471, 5472, 8621, 8854, 8865, 8938

Browse by section

Federal ExtensionsEvery federal extension form, in one place State ExtensionsAll 50 states + DC, Puerto Rico, plus 8 city/local jurisdictions, live now Interactive MapEvery state, Puerto Rico, and city pin is live Master MatrixEvery jurisdiction and tax type, one sortable table Penalties & InterestWhat still accrues even with a valid extension ResourcesOfficial IRS links and reputable e-file providers Estate & Inheritance Tax13 states + DC estate tax, 4 states inheritance tax Excise TaxForm 720, Form 2290 - no extension mechanism exists Sales & Use TaxAll 45 sales-tax states + DC checked - 33 no extension, 13 confirmed exceptions Other ExtensionsPayroll tax and FBAR FAQCommon extension questions answered
This guide is being built jurisdiction by jurisdiction, with every deadline, form number, threshold, and address verified against primary authority before publication. The federal section, all 50 states plus DC, Puerto Rico, 8 major city/local jurisdictions, state estate/inheritance tax, federal excise tax, federal payroll tax, FBAR, and a sales/use tax survey are all live. The estate/inheritance data now has zero open items, the SUI/SUTA survey covers all 50 states plus DC with zero open items, and the sales/use tax page covers all 45 sales-tax-imposing states plus DC - the master matrix shows current status.
This site is an independent reference maintained by the tk.cpa AI Lab. It is not affiliated with the IRS or any state tax agency.
This page is for informational purposes only and is not legal, tax, or accounting advice. No professional relationship is created by using this site. Tax law and IRS guidance change; verify against current primary authority before acting. Full disclaimer.
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