Given the connected nature of remote work these days, you likely use your home internet to do a little or a lot of work.
The rules that apply to the home internet also apply to all the other expenses incurred while working at home, regardless of whether you claim the home office deduction. 
Deduction on Schedule C 
If you operate your business as a sole proprietorship or as a single-member LLC, you file a Schedule C to report your business income and expenses. As a Schedule C taxpayer, you may deduct ordinary and necessary expenses, which include business-related internet subscription fees.
1 You can deduct your use of your home internet whether or not you claim the home-office deduction, as follows: If you claim the home-office deduction on your Form 1040, the internet expense goes on line 21 (utilities) of IRS Form 8829 as either a direct or an indirect expense.
2 If you do not claim the home-office deduction, enter the business portion of your internet expenses as utilities expenses on line 25 of your Schedule C.3 Deduction 
When You Operate as Corporation 
When you operate your business as a corporation, you are an employee of that corporation. Because of the Tax Cuts and Jobs Act (TCJA), the only way for you to reap the benefits of the home internet deduction (or a home office) is to have your corporation reimburse you for the deduction. 
In the case of a reimbursed employee expense,
– the corporation deducts the expense as a utility expense, and 
– you receive the reimbursement as a tax-free reimbursed employee business expense. 
Why is the reimbursement method the only way for the corporate owner to get the deduction? 
The TCJA eliminated the 2018-2025 deduction for miscellaneous itemized expenses. These include unreimbursed employee expenses, such as internet connection fees
Deduction When You Operate as a Partnership 
If you have deductible home internet expenses and/or a home office and operate as a partner in a partnership, you have two ways to get a tax benefit
– Deduct the costs as unreimbursed partner expenses (UPE) on your personal return. Or get reimbursed from your partnership via an accountable plan (think “expense report”)
Substantiating Your Home Internet Expense Deduction 
Where business owners can run into trouble with the IRS is in substantiating their internet expense deduction. Unless you have a home internet connection you use solely for business and also have another one for personal use, you can’t reasonably deduct your entire home internet connection expense. The IRS won’t believe you make no personal use of your sole home internet connection. We would not believe you either. You should have no problem showing the total cost for your home internet connection—just total your monthly bills. The problem is in establishing what percentage of the total cost was for business, because only that percentage is deductible. Ideally, you should keep track of how much time you use your home internet connection for business and how much time for personal use. A simple log or notation on your business calendar or appointment book—indicating approximately how many hours you were online for business each day while working at home—should be sufficient. Google it and you can find software and apps that will track your internet use. Instead of tracking your home internet use every day throughout the year, you could use a sampling method such as that permitted for tracking business use of vehicles and other listed property. 8 There is no logical reason the IRS shouldn’t accept such a sampling for internet use.