Hi Angela - see if this helps

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... there will be no contingent liability on the budget. ... del FEI in forza di tale meccanismo; non ci può essere impegno di firma sul bilancio. ...
eur-lex.europa.eu/Notice.do?mode=dbl&lang=en&ihmlang=en&lng1=en,it&lng2...236909:cs&page= - 111k - Cached - Similar pages

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Note added at 10 mins (2008-10-02 22:51:01 GMT)
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Sorry, here's the link
http://eur-lex.europa.eu/Notice.do?mode=dbl&lang=en&ihmlang=...

I would put a signed commitment or guarantee to cover debts. Would this fit with your context?

or "fidejussory guarantee" as below (between ****) from another proz post

Global Integrity ReportFor example, the second party in Italy (Forza Italia) is owned and mantained ( with a personal guarantee, "fidejussion") by Silvio Berlusconi, ...
report.globalintegrity.org/Italy/2007/scorecard/27 - 47k

fidejussory /fidejussion - Bürgschaft, Ausfallbürgschaft ... - [ Translate this page ]"Fidejussion 2nd sanction of European Commission" und der Satz: "Issue by the Credit Institutes of a ****fidejussory guarantee of xxx mln. ***elatively to the ...
www.proz.com/kudoz/english_to_german/finance_general/961007...

...

Sardinia Olbia Costa Smeralda AirportThe fee regarding to the minimum guaranteed and the storehouses are yearly ... A fidejussion is required, valid over 6 months after the expiration or the ...
www.geasar.it/eng/who_we_are/who-we-are/business-bring-your... - 54k -


fideiussione - WordReference Forums... which will guarantee payment for example, if a tennant does not pay rent etc . ... It's spelt "fideiussione" and it's a kind of guarantee, fidejussion. ...
forum.wordreference.com/showthread.php?t=625679 - 36k

ANTONINI & PARTNERS Italian Real Estate... of the loan and the type of additional guarantee beyond the mortgage bond. ... additional guarantees from third parties in various forms (fidejussion, ...
www.antoniniepartners.com/Inglese/Mutui0.asp?Lingua=2 - 30k - Cached - Similar pages

Hi Angela, the translation of the whole phrase "impegno di firma per garanzie sul debito is "loan guarantee", you might like to put "unsecured loan guarantee" orleave it out as just "loan guarantee" because if it was secured you would but "guarantees secured with collateral" or something like that.
If you considere this definition of "personal guarantee":
Promise made by an entrepreneur which obligates him/her to personally repay debts his/her corporation defaults on.

then if the person signing is personally liable it is a "personal guarantee".
Basically it is a "pledge by signature to guarantee the debt" but you are never going to say that in English.
If the "debito" in this case isn't actually a loan, but a specific debt (just six words of context is very little to go on) then guarantee of the debt might work. "power to sign to guarantee the debt".

In banking and finance the difference is between "crediti per cassa e per firma",which is loans (cassa) and guarantees (firma - with and without security). Big can of worms for a translator, but the reality is pretty simple.

P.s. I'm one hundred percent certain of what it is, the 4 confidence is because translating it is so tricky and context dependent (how do you like an off-balance sheet liability?).

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Note added at 9 hrs (2008-10-03 07:49:32 GMT)
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"The financial commitments are ....... (share capital + guarantee of debt)."

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Note added at 4 days (2008-10-07 03:58:04 GMT) Post-grading
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Investopedia definition of a "comfort letter"

"They are opinions and are not guarantees that the underlying company will actually remain solvent."
http://www.investopedia.com/terms/c/comfort_letter.asp

Investopedia definition of bank guarantee:
http://www.investopedia.com/ask/answers/06/202005.asp