the first question is are you a trader or investor? just because you consider yourself a trader doesn't mean the IRS will agree
Traders
Special rules apply if you're a trader in securities, in the business of buying and selling securities for your own account. The law considers this to be a business, even though a trader doesn't maintain an inventory and doesn't have customers. To be engaged in business as a trader in securities, you must meet all of the following conditions:
1) You must seek to profit from daily market movements in the prices of securities and not from dividends, interest, or capital appreciation;
2) Your activity must be substantial; and (generally it's recommended that there be over 1,000 trades a year but the courts let trader status fly for one who only did 700 - but then he also had another full-time occupation while trading in his spare time)
3) You must carry on the activity with continuity and regularity. (doing 20 trades on Monday and nothing the rest of the week won't fly)
4) The following facts and circumstances should be considered in determining if your activity is a securities trading business:
a. Typical holding periods for securities bought and sold;
b. The frequency and dollar amount of your trades during the year;
c. The extent to which you pursue the activity to produce income for a livelihood; and
d. The amount of time you devote to the activity.
If the nature of your trading activities doesn't qualify as a business, you're considered an investor and not a trader. It doesn't matter whether you call yourself a trader or a day trader, you're an investor. A taxpayer may be a trader in some securities and may hold other securities for investment. The special rules for traders (that make the mark-to-market election) don't apply to those securities held for investment. A trader must keep detailed records to distinguish the securities held for investment from the securities in the trading business. The securities held for investment must be identified as such in the trader's records on the day he or she acquires them (for example, by holding them in a separate brokerage account).
Traders report their business expenses on Schedule C (Form 1040 or 1040-SR), Profit or Loss from Business (Sole Proprietorship). Commissions and other costs of acquiring or disposing of securities aren't deductible but must be used to figure gain or loss upon disposition of the securities. See Topic No. 703, Basis of Assets. Gains and losses from selling securities from being a trader aren't subject to self-employment tax.
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if an investor then the expenses are not deductible,
if you were a trader in a previous year, the items were deductible in the year paid. you can't deduct expenses paid in prior years in 2021 but you can amend previous years
