Can I file tax returns for previous cash income made between 2014 and 2018? If so, what are the penalties? Let's say I made 15,000 during each of those years. Thanks!

[no.11]

Also, what proof of income would I have to provide? It would be difficult to actually get an accurate number. I need to do this in order for my experience to count and meet minimum requirements for a job. I'm willing to pay the penalties, I think.

[xmasbaby0]

Seek professional paid tax help.   TurboTax has software going back only to tax year 2018.   Software is no longer available nor supported for earlier years.

What if I do not file my tax return?

https://ttlc.intuit.com/questions/2572308-what-happens-if-i-don-t-file-my-taxes

You do not say what type of work you did during those years.   If you worked as an employee you need your W-2's that would have been issued by the employers each year.   If you have been self-employed then you may need any 1099Misc forms that were provided to you, or you might have to rely on your own records---such as they are.

You can get a wage and income transcript from the IRS:  It will not show the actual W-2, 1099’s, etc, but will show the income information the IRS received.  It will not, however, show your state information. It will only show the federal information.

https://www.irs.gov/individuals/get-transcript

[Opus 17]

We need more details about your work and income.

I will make one guess and give you an answer for that guess.  For any other situations, you will need to give us more details.

I will guess you were self-employed and paid cash under the table.  In that case, you are required to file a tax return and pay self-employment tax if your net income (gross income minus expenses) is more than $400.  SE tax is about 15% of your net income.  You are expected to keep your own accurate business records of your income and expenses.  You would probably owe very little income tax on top of the SE tax, based on those income levels.  

The penalty for failing to file a tax return is 5% of what you owe for the first 5 month, then 0.5% per month thereafter.  The penalty for failing to pay the tax you owe is 0.5% per month.  Then there is overall interest on the whole amount owed of about 4% APR.  For a 2014 tax return, due April 15, 2015, your penalties and interest would be about 1.4x the amount of tax owed, so if you had $10,000 of self-employment income, you would owe $1500 of SE tax and about $2100 in interest and penalties.  The interest and penalties would be less for each succeeding year since there was less time for them to accumulate.  

The IRS might accept an offer in compromise (take less money because you are coming clean and paying your taxes).  You could file your returns by hand using forms and instructions downloaded from the IRS web site, and you could even contact the IRS about your offer, but you might be better off working with a tax professional who could prepare your returns and work with the IRS to reduce the penalties and interest.  

Besides getting your work on the record for your current reason, filing these back returns will give you social security credit toward disability and retirement.  It's also worth noting that the statute of limitations for the IRS to audit you is normally 3 years from when you file, so if you never file, that clock never starts running and you can be audited forever.

Although it is theoretically possible to do this yourself, I really suggest professional help.

If you are talking about some other kind of situation, we will need to know more details. 

[Hal_Al]

Assuming you were not claimed as someone else's dependent, roughly the first $10,000 (standard deduction and personal exemption) was not subject to income tax.  So you owed about $500 of income tax ($15,000 - 10,000 = 5000 x 10% = $500). 

But, if it was self employment, no social security and Medicare tax was withheld and you need to pay that, in addition to income tax.  Self employed people pay their social security and Medicare tax in the form of "Self Employment tax" (SET).  It's an odd calculation but is roughly 14% of your net self employment income. $15,000 x 14% = $2100.

$2100 + 500 = $2600 per year plus interest and penalties. 

[no.11]

Thanks everyone! 

The type of work I was doing was construction; sheet metal and HVAC work, and at the time I also had two part-time jobs for which I did pay into taxes. 

For the construction work, I was self employed and didn't report any of it at all. 

[Vanessa A]

Yes, you can still file.  You would need to purchase a desktop version of TurboTax from Amazon or another retailer for those years.  You would have a Failure to File Penalty and a Failure to Pay Penalty.

Depending on the rest of your tax situation, the penalties and interest may be minimal or a lot. If the payment due is too high, you can apply for a Payment Plan. 

The sooner you file, the better as fees and penalties accrue monthly. Also, the IRS can come back at you any time for a return not filed and charge you the penalties and interest whether or not you file so it is better to get it done sooner than later. 

[Opus 17]

@no.11 

Then you would need to file amended returns for those years to add your self-employment income.  You would owe self-employment tax plus income tax plus penalties.  (I don’t think you pay failure to file, but you pay failure to pay penalty.)  As before, you can technically do this by hand but you probably want professional assistance to help with the penalties.