Chunking works by throwing large irregular payments at your principal. A prepayment penalty is a fee the lender charges for doing exactly that. Before the first chunk, find out whether your loan has one, because the answer changes the size and the timing of everything after it.
On an owner-occupied qualified mortgage, the rules got tight after 2014. A qualified mortgage means one that meets the federal standards most ordinary home loans are written to. Most conventional loans written since then carry no prepayment penalty at all. Where they still live is the paper outside that box: investor and rental property loans, DSCR loans that qualify on the rent rather than on your income, bank statement loans, some portfolio loans from small banks, and hard money. If you bought a rental with a loan like that, assume there's a penalty until you've read otherwise.
Look in two places. Your Closing Disclosure, the form you got at signing, has a box on page one that says whether the loan has a prepayment penalty, yes or no, and how long it runs. Then the note itself spells out the math. The common shapes are a percentage of the amount you prepaid, a set number of months of interest, or a step-down, meaning 3% in year one, 2% in year two, and 1% in year three. Commercial paper sometimes uses yield maintenance, which makes you cover the interest the lender expected to earn, and that one gets expensive fast.
A lot of these come with an exemption that changes the whole plan. Many let you prepay up to 20% of the original balance in any twelve-month period with no penalty, and charge you only above that line. If your loan reads that way, you don't stop chunking. You size the chunks to stay under that limit and you spread them across calendar years. A $300,000 loan with a 20% allowance gives you $60,000 of penalty-free principal a year, which is more than most households can send anyway.
Lines of credit have their own version, and it isn't called a prepayment penalty. It's an early termination fee or early closure fee, and it triggers when you close the account within the first two or three years. Usually it makes you pay back the closing costs the lender waived when you opened it. That fee doesn't punish you for paying the balance down. It punishes you for closing the account, which is a different behavior and an easy one to avoid. Pay the balance to zero and leave the account open. The fee schedule that spells all this out is the one in read the fee sheet before you sign for a line of credit.
Call your servicer and ask two questions in this order. Does my loan have a prepayment penalty, and if it does, will you send me the language. Then, can you give me a payoff quote that assumes a $40,000 principal payment next month, and does that quote include a penalty. The second question gets you a number instead of an opinion, and a number is what you need to weigh against the interest you'd save.
If there is a penalty and it steps down, the answer is usually to wait it out. Paying the mortgage normally for three years and then chunking hard beats paying 2% for the privilege of being early. Run both versions before you decide, the same way as run the numbers before your first chunk.