Mortgage acceleration is a term given to the practice of paying off a mortgage loan

Mortgage loan

A mortgage loan is a loan secured by real property through the use of a mortgage note which evidences the existence of the loan and the encumbrance of that realty through the granting of a mortgage which secures the loan...

 faster than required by terms of the mortgage agreement. As interest on mortgages is compounded

Compound interest

Compound interest arises when interest is added to the principal, so that from that moment on, the interest that has been added also itself earns interest. This addition of interest to the principal is called compounding...

, early payments diminish the period needed to pay off the mortgage, and avoid a quotient of compounded interest.

In addition, acceleration may refer to a clause in a mortgage note

Mortgage note

In the US a mortgage note is a promissory note associated with a specified mortgage loan; it is a written promise to repay a specified sum of money plus interest at a specified rate and length of time to fulfill the promise...

 that allows the mortgage holder to declare the entire debt of a defaulted

Default (finance)

In finance, default occurs when a debtor has not met his or her legal obligations according to the debt contract, e.g. has not made a scheduled payment, or has violated a loan covenant of the debt contract. A default is the failure to pay back a loan. Default may occur if the debtor is either...

 mortgagor due and payable.

A commonplace method of mortgage acceleration is a so-called bi-weekly payment plan, in which half of the normal calendar monthly payment is made every two weeks, so that 13/12 of the yearly amount due is paid per annum. Commonplace too, is the practice of making ad hoc

Ad hoc

Ad hoc is a Latin phrase meaning "for this". It generally signifies a solution designed for a specific problem or task, non-generalizable, and not intended to be able to be adapted to other purposes. Compare A priori....

 additional payments. The agreements associated with certain mortgages preclude or penalize early payments.

However, another type of mortgage acceleration concept appears to have been embraced by a variety of financial institutions and intermediaries, which offer products such as methods, software, mortgage-linked checking accounts, and home equity line of credit loan facilities advertised as being capable of assisting in achieving mortgage acceleration, and available at a range of premiums.

Most of these “mortgage acceleration” (also called “mortgage reduction”, “interest reduction” or “debt reduction”) programs or software are based on a trick.

The basic claim made is that by using a particular type of loan in a particular way (often following a “program”), the borrower can cut many years off the mortgage without making additional repayments – or similarly, that although additional payments are made, the savings increase significantly due to the use of a particular loan and/or strategy.

The concept usually involves a type of loan that allows the borrower to use the loan as their day-to-day transaction account. This loan may refinance the entire mortgage, be in addition to the mortgage (requiring regular transfers to the mortgage) or in some cases involves an “offset” account, that sits separately to the mortgage but offsets interest on any deposit against the mortgage interest.

Promoters can profit from the sale of software, providing “monitoring” or “support”, or from commissions from referrals to lenders. Examples are usually presented that show huge savings on the mortgage. These examples may be based on the borrower’s estimate of their regular expenditure, or on an “example” family. An underestimate of real expenditure (by the promoter or the borrower) leaves additional amounts in the mortgage (or related account) in the example, and the example therefore shows significant savings. However, the presentations represent that the savings are primarily due to the type of loan account and the way it is being used.

In theory, savings could be made by leaving funds that would otherwise be in a transaction or check account for bills and living expenses, in a mortgage or related account. For example, if a borrower had an average of $4,000 sitting in a check account, leaving this in their mortgage or related account could save about $280 per year on a 7% mortgage - or less than $6 per week.

Even $6 per week can make a difference to a mortgage in the long term, but there are almost always some costs involved in setting up the “program” and these will usually exceed the savings. Costs may include fees and interest incurred in relation to a separate line of credit loan, or in refinancing a mortgage. Interest and/or monthly fees on the new mortgage may be higher than on the old mortgage. The cost of software to “monitor” the program, or fees paid to set the program up will also reduce the meager savings that can be made.

While some promoters refer to the Australian experience, this type of marketing has all but ceased in Australia since the Australian regulator, the Australian Securities and Investments Commission (ASIC) took action to stop a range of brokers and software developers from making the above representations.
http://www.asic.gov.au/asic/asic.nsf/byheadline/02%2F428+Westpac+agrees+to+alter+Rocket+Home+Loan+campaign?openDocument
http://www.fido.asic.gov.au/fido/fido.nsf/byheadline/07-144+Court+finds+major+mortgage+broker%E2%80%99s+conduct+misleading+and+deceptive?openDocument
http://www.asic.gov.au/asic/asic.nsf/byheadline/04-300+No+credit+for+misleading+loan+calculators?openDocument
http://www.fido.gov.au/asic/asic.nsf/byheadline/07-95%20asic%20obtains%20injunctions%20against%20loan%20calculator%20operator

One such program points out the fact that people hold cash for emergencies and day-to-day spending in accounts that earn smaller returns. Why do they do this? This is done because immediate access to cash is needed: consumers are paying an Opportunity Cost to have the cash close at hand. A HELOC can provide similar flexibility since you can pull from a HELOC on-demand as if it were a checking account. Thus, you can actually take the cash you have on-hand and pay down your first mortgage, then draw from you HELOC when you need cash. This generally produces a better return, but it depends on your rates:
In the US, mortgage and HELOC interest paid is tax deductible (be careful of Alternative Minimum Tax

Alternative Minimum Tax

The Alternative Minimum Tax is an income tax imposed by the United States federal government on individuals, corporations, estates, and trusts. AMT is imposed at a nearly flat rate on an adjusted amount of taxable income above a certain threshold . This exemption is substantially higher than the...

), whereas interest the bank pays you from a savings account is taxable. For example, if you're in a 25% tax bracket and have a HELOC tied to prime + 1 (=6%) the effective interest you pay to the bank is 4.5%. On the other hand, if you're earning 4% on your savings account, your effective yield is 3% because you have to pay 25% of that yield to the government. The return is a full 4.5% from any cash you divert away from checking. Thus, and cash you put toward your HELOC or first mortgage rather than checking/savings will net you a 1.5% advantage. However, there are a few ways this can backfire:

1) the bank may freeze your line of credit (this has been happening since the Credit Crunch)
2) you may become subject to Alternative Minimum Tax
3) the benefit will change based on your income tax rate, savings rate, checking rate, mortgage rate, and HELOC rate (which is generally tied to Prime)